Edgar Wright, Brad Bird, Chris Nolan more
Pro: Did you see "District 9"? This guy could crush it, and one thing that's fun about his work is that grimy dirty quality to the technology in it. That was one of the things that many fans fell in love with when they saw the original "Star Wars," and it was perhaps the single most imitated thing about the film. Without "Star Wars," there is no "Alien." That worn-out look was missing from the prequels, but that was because they took place earlier than "Star Wars." If "Episode 7" is going to be set after "Return Of The Jedi," then we're talking about a galaxy that is rebuilding after a war, and there's no one working right now who does that sort of grimy functional thing better than Blomkamp.
Con: After his experience on "Halo," Blomkamp seems reluctant to work with someone else's material. We have so few guys working right now to make original science-fiction films that it might be a bad idea to tie up someone with a voice as strong and interesting as Blomkamp with someone else's property, even if it is "Star Wars."