From TheOneRing.net :

PJ ‘may direct The Hobbit’: Sir Peter Jackson says he will step into the breach and direct The Hobbit himself if it becomes the only way to ensure the US$150 million (NZ$219m) film is made after the sudden departure of director Guillermo del Toro.

Well, that’s something I guess. I’ve also read that he can’t because of contractual issues with other movie companies. Someone I read recommended Alfonso Cuaron…. now THAT could be interesting too. Keep your fingers crossed.