http://xbox360.ign.com/articles/105/1055366p1.html
at the end it mentions how part three of the trilogy might be a completely different game depending on how you finish 2, saying the differences are even more pronounced than what happens in 2 as a result of what happened in 1.
hmmm.... i doubt they will stick to this, people will whine too much, if they do it I expect to be able to choose at the beginning, ESPECIALLY those people who never played 1 or 2 - they'd be getting screwed out of a big chunk of the game.
that said, it sounds cool just because its such a nutso idea