7. Rian Johnson
Why it could be him: Rian Johnson's star is on the rise, big time. After only three films, he's proven to be a filmmaker with a unique voice, and the ability to turn in a quality film with great performances from all involved. Plus, if you saw Looper, you know he can handle the themes and subtext that go hand in hand with the best sci-fi.
Why it won't be him: He's only made three films, that while awesome in their own right, haven't fully prepared him for what a new Star Wars film would take. Not saying he won't get there with time, but if they were hiring right now, this would count against him. Also, he's really a big fan of developing his own scripts and doing his films his way.