In hindsight, I think the main problem with Revan and what to do with him is the fact that if they (the collective "they" of all the people involved in the KOTOR series) wanted to base the story around him or make him an integral part, they should have planned better and made levelling him at a slower pace possible so he could be the PC for all 3 games. That, to me, was the only plausible way that Revan could be a big part of all three games without having to mash together an incoherent story just to insert Revan's name in it.
Since that wasn't the case, Revan needs to become a "secondary" character, rather than a prominant NPC. The moment they levelled him up too fast in KOTOR I was the moment he went from being "Luke Skywalker" to "Yoda", and from here on out it's probably best if he's only used as a Yoda type character (not really central to the story, just there for the odd cameo of advice and/or confrontation).
Truth be told, I have no idea what the best storyline would be to wrap up the "Revan" saga. I'm not sold on the idea that it would be best to just kill him off, and I'm also not sold on the idea of having Revan be such a focal point as a NPC or whatever, either. Thank God I'm not the one writing the story for KOTOR III (if there is one).