I'd love to see Hamil, Fisher and Ford play the characters again, with no kids or already established secondary characters. The EU already did their families and the general story just fine, abrams needs to leave it alone. I hope whatever Abrams poops out is harmless enough to leave the good Star wars stuff alone. Best case scenario, they just have the old three go on an adventure, and be really nonspecific about dates or events between episodes 6 and 7. That way, we can at least see the old actors being cool, and I'm not sure if even Abrams can screw up Ford or Hamill, their performances would probably be good regardless of who wrote the script or directed. I'm not sure about Fisher, but honestly she doesn't seem like someone who'd want to come back anyway, although she apparently has done a bit of acting in recent times.
That's assuming we get the old three back. If not, and its just a story with younger actors playing the trio, there isn't much to be done, except to at least try to not be as stupid as some of the prequel stuff. In this scenario, just not having a lame comedy relief character like Jar Jar is about the best that could be hoped for. I may think Lucas is a better writer/director than abrams (and Lucas isn't very good), but even Abrams can learn a little bit from Lucas's prequel mistakes. I would honestly be surprised if we get a movie as bad as Episodes 1 or 2. More infuriating, and more damaging to the Star Wars universe? Absolutely possible/probably, but taken by itself, thinking about it honestly, it will probably not be as bad of a movie as the first two prequels, regardless of what it does to the franchise.