Source: Superhero Hype!
This is just pure speculation, but Sam Raimi has been saying for a while now that if Peter Jackson decides to produce The Hobbit for New Line instead of direct it, that Raimi hoped he would get a chance to take the director's chair.
Well, the big news has finally hit this morning -- Peter Jackson will produce (not direct) The Hobbit and a sequel to The Hobbit. Full details can be found here.
If Raimi decides to helm "The Hobbit" films instead, we would assume he would still be involved with the Spidey franchise in some capacity, probably as an executive producer.
Again, this is just speculation and nothing is certain.