Spoilers in this post for FF13:
The whole plot of the game could be set up to help save Vanille/Fang or at least part of it, I am sure there will be a new overarching plot but in the sequel Fang/Vanille won't be in most, possibly all of it. Fang was a very popular character so she will be missed, I don't think that many people liked Vanille though so I don't think thats much of a problem. Out of the original cast I'd like to see Lightning and Sazh come back, then some new cast members.
With FFXIII-2, it will be interesting to see how they approach it, because the game is about civilizing Pulse and conquering hardships of building a new civilization along with fighting with the harsh Pulse environment. The scenario has lots of gameplay and plot potential, lets hope they can deliver on that. I think we can definetely expect a more traditional game as the makers of FFXIII stated their next title would be more traditional from the perspective of Towns and non linear structure. If done right a FFXIII-2 could be a very good game.
We might get the first reveal for it on Tuesday and the Square-Enix conference, if not there E3.
