I like the Ideas you just gave...but, I would feel cheated if Revan was not the PC PC. There is a connection with the character, and personally I would rather finish his story off myself, rather than having to get connected to a new character who finishes the story for him. Quite frankly, this saga is really about him, and lets be frank, most of us were quite pissed not being able to be/use him in KOTOR II. I WANT TO BE REVAN AGAIN. He was far more interesting than the Exile, who was still quite interesting in his own right.
What I would want would be something along the lines of: Prior to the start, you get to choose Revans alignment. First we get the necessary story role which explains what Revan has been up to for the past years (It changes depending on whether you picked LS or DS for Revan). The start of the game would be a cinematic of Revan (in his personal robes w/mask) entering into a sith temple to confront a very powerful sith lord. As he approaches the Sith lord he is attacked by the apprentice of the Sith and dispatches the apprentice with ease. He then engages the Sith lord in combat and we see them use a number of force powers (new and old)on each other while also dueling with sabers (which powers revan uses depends on his alignment which was chosen). Needless to say, it is a ferocious battle, which ends with Revan finally striking down the sith lord, only to fall to the ground from his own wounds (though he is not dead). Following this we see the T3 and HK-47 enter the temple and go towards Revan (we see the body of the Sith apprentice and the Sith Lord) before finally we see them come to the body of Revan (who is alive, but very injured). You see HK-47 and T3 carry the body of Revan out of the temple and into their ship (be it new or the Ebon Hawk, it doesnt really matter to me...personally, for continuities sake, I would like the Ebon Hawk). Then the game actually starts.
The First Planet you are one you start with only T3 and HK-47. The mission on the first Planet is to actually revive Revan (who has in a Jedi Trance to survive the injuries that were sustained). Unfortunately, the droids are unaware as to how to actually bring someone out of the trance, but they know from their experiences with Jedi, that they need the help of a Force Adept. They have heard (or hear during the game) that their are rumors of a being killing off the sith on the planet in search of the one known as Revan (though none on this sith world even know who this Revan is). As a result the two droids go through much of the first planet in an attempt to find this being (because if they reveal themselves or Revan to the sith, the Sith will kill him, because he is trying to purge them (LS) or kill their leaders and rule them (DS)). Basically in the end of the planet we discover the "being" killing off the sith is actually Bastilla Shan who has come to find Revan.
If Revan was DS, she comes anyways as the sith holocron explains, but, if Revan is LS, then she will explain to Revan, the Exile, after defeating the Sith Lords Nihilus, Sion, and Traya, gathered all of his allies, and Revans allies in an attempt to find Revan. The Exile ordered all of these allies to split up and scatter throughout the galaxy in a desperate attempt to find Revan so that they may shore up the defenses of the Republic in order to fend off the immenent attack upon the Republic from the True Sith as Traya explained they would do). Bastilla explains all of this to Revan as she brings him out of the Jedi Trance. If Bastilla came on her own (Because Revan was DS) then HK-47 should explain it as Revan is brought out of the trance. At this point we gain control of Revan as the PC and get to pick all of the force powers from lvl 1-20 to start with. The reason I would keep the lvl 20 is because that was Revan's Max attainable lvl in KOTOR I, and so we dont have any of this crap amnesia or cut off from the force crap, yet still use Revan. In order to compensate for this, I would make the enemies tougher (seeing as they are the "True Sith" they would be stronger) and make the level progression slower, so that the it would take the entire game to gain 20-30 levels (finishing the game at level 40-50). At level 25 you will be allowed to choose a prestige class for revan. BTW, when you enter the character screen, we see that Revans alignment is only halfway to the light/dark (depending on alignment), not fully mastered in LS or DS due to many events which took place...but of course we get to chance that throughout the game.
Here we are allowed to change direction of the story, one way or the other. If Revan starts off LS, he will be given the choice of slowing the Sith attack by finding and destroying the dark lord of the Sith and throwing them into chaos; or turning evil and declaring that he will take the mantle of Dark Lord (from the current Lord) and end the republic. If Revan were DS, he is given the same choice, thus changing the game in the middle.
You know that the only means of finding the hidden Dark Lord (who controls his empire through his apprentices whose locations are known as they are the leaders of each planet in the game (the dark lords way of controling his emipire)...though no one apprentice will have the full set of coordinates to the dark lord, thus ensuring the ability to protect the dark lord, and hence the leadership of the Empire. Throughout the game you visit a whole host of worlds in order in an attempt to hunt down and destroy the leadership of the Sith Empire (killing off various apprentices of the Dark Lord as the main fight on each planet), and slowly finding clues as to the location of the Dark Lords stronghold.
On each planet you will gain an ally, some new, some old. The allies are a mix of those who were with the Exile, and those of Revan. Those who should definately make their reture (other than HK-47, T3, and Bastilla) are Mandalore, Carth, Bao-Dur, and Handmaiden (Handmaiden and Bao-Dur should be a Jedi, trained by the Exile). You also should get 3 more allies (new to the game) just to keep things fresh...none of these 3 should be jedi but regular people...but each will have the potential to be trained as a jedi by Revan if he gains enough influence on them. Again the Influence will be used to unlock sidequests and open non-jedi (except Carth and Mandalore) up to become jedi, as well as turning Bao-Dur and Handmaiden to the darkside (if you are DS).
After all the apprentices have been defeated, the final coordinates of the stronghold is discovered, Revan is stunned to discover that the stronghold of the Dark Lord is non-other than Korriban. He then realizes that the powers preception (his and that of the jedi) have been somehow impared by the Dark Lord of the Sith, in order to hide his stronghold right under thier noses, without them realizing it. They make their way to Korriban to confront the Dark Lord, though the action takes place in a different (hidden) location on the planet, other than Dreshdae and the Sith Academy, that is why we havent seen it before. The Party must be include Revan and Bastilla. Revan and party fight their way throught the stronghold of the dark lord fighting many sith lords and dark jedi along the way until we reach the part of the stronghold and are confronted by the apprentice of the Dark Lord who strikes from the shadows, severely injuring the third party member (other than Revan and Bastilla) so much so that they are unable to continue. The Apprentice is shrouded in all black, and wearing a mask that resembles that of Nihilus, though isnt exactly the same. After defeating (though not killing) the apprentice, the Dark Lord of the true Sith enters the area and walks over to the apprentice. Its the Exile!!!!!! He says something like "You were always too weak and pathetic...You have failed me for the last time!" and uses force crush to deal the deathblow to the apprentice, when the body falls to the ground the mask falls from the face and we see that the apprentice was actually Visas Mar!
The Exile then explains that during Mandalorian wars he had discovered the location of the true Sith empire, that is why he went back to face the jedi (to tell them of what he had discovered). But when he saw how he was treated by the council (with arrogance and scorn) he saw nothing but the weakness he knew was always in them, and he hated them for it. When he was exiled he resolved to destroy the jedi. In the years between his exile and return to the republic he became the dark lord of the true sith and returned to the republic with the plan to root out Revan (the only one who had the power to stop him at the time). Only he found that Revan was missing. The Exile had found sources of power within the dieing republic that could in time pose a threat to him (Bastilla (depending on Revan being LS or DS), Bao-Dur, Handmaiden, Carth (with his growing Republic fleet), and Mandalorians (who were recovering from the Mandalorian Wars), aswell as the three Sith Lords (Traya, Sion, and Nihilus). He vowed to wipe out the Sith Lords and remove any threat to him by sending them on a hunt for Revan, thinking it would be too late to save the republic by the time they find him. Basically the Exile sent Bastilla (if Revan was LS), Bao-Dur, Handmaiden, Mandalore, and Carth out because they were the only ones capable of stoping the exile, so he needed them out without outrightly killing them, which would tip off the republic to his immenent attack. He did not count on them finding revan before the attack and even less so on Revan leading them straight to him...but he states that it is too late for Revan to stop him, and that he has learned much since the time he served under Revan during the mandalorian wars, such as the ability to rip the force out of living beings using his connections to them...and he has connections to everyone in Revans party (including Revan) as he was the one who sent them to find him, and they trusted him enough to follow his orders. He attempts to kill revan, but Revan is saved by the Bastilla, who sacrifices her own life to protect Revan...leaving Revan alone to fight the Exile (seeing as Visas injured the third member of the party). Then you get another chance to change the direction of the story (stating your intentions...save the republic, or assume the mantle of dark lord by killing the Exile and then using his forces to end the Republic). You (as Revan) fight the Exile. When you kill him you get the ending sequence (depending on LS or DS) you get to either save the republic (who sends in multiple fleets to bomb the crap out of the sith military bases on each planet you visited and you see the jedi temple on Courasant and a new jedi council made up of Revan, Bao-Dur, Handmaiden, Mira, Vandaar, Zhae (or whoever the twilek master from KOTOR was), and a few other nameless Jedi. Or you see Revan on the bridge of his flagship at the head of the new sith fleet. And you see the fleet attack Dantooine (again), Telos (again), Onderon, and then you see the massive fleet converge on Courasant and it ends the game.