I figure they'd do separate levels in that case. Something similar to the official ROTK game.
After the first level of that game, the "level tree" started to split up. You had to select which of the levels you wanted to play,
and if you completed that level you could go further in the selected character group's journey - so Gandalf's journey and that of the Hobbits were separated. If you did a level featuring Gandalf, then you couldn't go to the next Hobbit level, but just his.
I don't know if they'll do it this way, because there would have to be many levels, but if they did it would make for a longer game, which should be good.
If they don't do it like that, then I'm sure it will be fine regardless.
~ General Magma
Edited by General Magma, 15 June 2012 - 02:10 PM.