My sole worry is that Abrams will do something to totally invalidate the years of EU writing - Thrawn, the Vong, the Second Galactic Civil War - and just come up with something that, while decent, nonetheless puts it front and centre under the label 'canon', and make everything else irrelevant or wrong.
Apart from that...Krayt would be interesting, but probably never going to happen, particularly since he didn't emerge as a Sith Lord until way after the Yuuzhan Vong War. But I have a feeling it'll be something to do with re-establishing the Jedi Order, since that would be the obvious pathway to go: Ep1 with the Order at it's height, followed by it's decline, followed by Luke becoming a Jedi, with the re-emergence of the Jedi Order as a power being the natural follow-through. Not like there aren't a ton of stories you could potentially tell there.
Oh, and did I mention that we want Corran Horn?