eeek, I hate it when good Characters die, although it can be very necessary to add to the drama and further the plot.
Even though I am a fangirl I realise that if they had left in the death scene of Atton (female pc) in TSL it would have serious impact and given a very powerful ending to KotorII. So even though it would be sad it would have added a "wow" factor that just wasn't there.
I think Revan and the Exile should die heroically saving the Galaxy or defeated horribly for turning to the Dark Side, depending on how you played the game.
This would then given a chance for further characters to continue Kotor or close the door completely.