It's been said, quite accurately, that the KOTOR series is quintessentially Revan's story - while the Exile is important in TSL, by the end we get the impression it's Revan that really matters. It's worth keeping in mind though, that the Revan that it's about isn't the Revan we played in KOTOR 1 - that was a temporary Revan, finding him/herself. The stuff Revan did that mattered, by the end of TSL (not surprisingly, considering the Obsidian folks couldn't write two COMPLETELY different storylines), was the stuff he did while we weren't playing him/her - during the Mandalorian Wars, shortly afterward, and later, after he/she left again for the outer rim.
I guess what I'm trying to say is that while it's definitely Revan's story, we've always seen it from another perspective - even when we were Revan ourselves. That's what made some of it so powerful - he was our character, but there was enough out of our control for the developers to write a real story we could react to, not just a cardboard choose-your-own adventure. To a certain extent, while I got attached to the Revan I played in KOTOR 1, and wanted to continue with that character when I finished, by the end of TSL I realized that (at least for me), Revan's real story - and the story of the series - was the story I hadn't participated in . And, of course, having just finished TSL, I'm quite attached to the Exile, who makes a nice perspective to view Revan's story from - but if the developers of KOTOR 3 can't make that work from a gameplay standpoint, I think I can trust them to do a good job with a new protagonist. After KOTOR 1, I would have thought having anyone but Revan as protagonist would be "bad storytelling". Now, though I know I'd like to play as the Exile again, I'll wait until I actually see their storytelling before I judge it. No offense intended to those who are making that judgment - maybe I'm just more optimistic - but I wouldn't give up hope on the game if it's got a new protagonist, especially if it's developed by a company like Obsidian or Bioware.