It's only just the rumor but according to Collider there's a big chance that X-Men First Class director Matthew Vaughn is on the top of the short list of Episode VII directors:
I’m hearing that Matthew Vaughn, the director of Kick-Ass, Stardust, Layer Cake, and X-Men: First Class, is in talks with Lucasfilm to helm Episode VII. My sources tell me this is the main reason he dropped out of the X-Men sequel. Hit the jump for more.
Now you have to ask yourself, why would Vaughn abruptly drop out of helming the X-Men sequel when the head of 20th Century Fox (Tom Rothman) is leaving the studio? After all, while Rothman helped make some great movies over the past few years, he’s also known as a micro-manager that can rub some filmmakers the wrong way. With Rothman out, I imagine Vaughn would have had more creative control on the sequel and it would have been an easier film to make.Source: collider.com
But if Lucasfilm offered Vaughn the keys to Star Wars, that’s something he’d likely jump ship for.