Going to go into a pro/con about having the original actors in Episode VII
-New actors portraying the original characters could generate new fans (See Star Trek)
Why is this a con..?
Like Star Trek fans, Star Wars fans are passionate, caring lot about their favorite property. The 2009 Trek film wasn't and hasn't been fully embraced by the hard core fans, and it could do the same for Star Wars. While I doubt the Star Wars reality will be altered (like Star Trek was in 2009), the hard core fans and the fans of the EU might not embrace the changes that will occur. Trek fans feel William Shatner is their one and only Captain Kirk. Chris Pine did a great job portraying Captain Kirk, and he is a better actor than Shatner, but hard core fans don't accept Pine. IMO, the same thing will be with a new cast-it could generate new fans, but the passionate, hard core fans may not like the new actors, or their interpretation of beloved characters. Sure you get new fans, but will they buy new merchandise, will they buy updated novels and comic books detailing thier new adventures? The hard core fans will. Star Trek is learning that now, it took 2 years after the release of the JJ film to do a follow up comic book series, because despite getting all the new fans, they wouldn't support any follow up material. That's why the novels that keep coming out are based on the unaltered Trek universe, and uses the OS epeisodes as canon. So, that's why I think it can be a con.
Of course we sci-fi geeks can be a bitchy lot.