The current talk of the town via THR, is that the major script rewrites for Star Wars: Episode VII by Abrams and Larry Kasdan will focus on making the the original three actors (Hamill, Fisher and Ford) the main leads. Placing the new characters in supporting roles, before eventually taking over in Episode VIII and Episode IX. It's said that Michael Arndt's script would focus mostly on the Skywalker kids, and having the original cast act as mentors to launch the new trilogy. That seems to have been scrapped, and Abrams along with Larry Kasdan are trying to make Luke, Leia and Han the leads of the film, before handing the franchise over to a new group of actors. I wouldn't be shocked if bits-and-pieces from Arndt's script end's up being used for Episode VIII.
Of course, with rewrites that means new characters will be created, and others cut from previous drafts. A new casting report from reports that J.J. Abrams and Lucasfilm are looking at Michael Fassbender (12 Years A Slave, Shame, Inglourious Basterds), Hugo Weaving (Cloud Atlas, Matrix, V For Vendetta, Lord of The Rings, Hobbit), Adam Driver (Girls, Frances Ha). Weaving could end up playing an Imperial character in the film.
Breaking Bad's Jesse Plemons (The Master) has also been linked for an upcoming meeting with J.J. for a lead role, according to TheWrap. My guess would be that Plemons might be up for the role of Ben Skywalker.
Fassbender is the third cast member of 12 Years A Slave to be linked for a part in Episode VII. Previously, Benedict Cumberbatch and Chiwetel Ejiofor have been reportedly pursued for roles in the film. Ejiofor seemingly confirms interest to Yahoo! (via CBM), instead of the usual denial we get from candidates (I'm taking about you Cumberbatch). A possible Oscar nomination is on the horizon, which could see Chiwetel getting a ton of offers for big movies after the awards ceremony. Nabbing him early would be a smart move on the part of Lucasfilm. Ejiofor has also been a fan-favorite for the role of T'Challa in Marvel's Black Panther film, which may or may not be in the works for Phase Three.
"Who knows? We'll just have to see...I don't know is really the only answer I can give you. I'm a huge fan of that world and JJ, but I don't know. I can't tell you. There are a lot of things that would be great to play and to investigate if I spent enough time thinking about it, but really it's to try and see what actually does happen, what materialises... and figure out what the great stories are."
Having actors on this kind of level will likely help, rather than hurt, considering there would be less of a gamble acting-wise if Lucasfilm hires awards caliber actors for roles. Fassbender's involvement with the X-Men franchise could become a conflict, along with his participation with Fox's Assassin's Creed film. That being said, Michael is a workaholic and cramming a bunch of lengthly productions next to each other, wouldn't be a problem for him.