Nice call, Sauce -- I was going to mention Gilliam myself. He would certainly be an interesting choice -- better than Burton IMO.
Further to the question of actors and a Jackson-less
Hobbit, I just saw this article:
McKellan "sad" that Jackson may not make "Hobbit". Notice how Sir Ian doesn't say he would never do TH without Jackson. And anyway, I seriously doubt that Jackson would want anyone to pass up the job for his sake. It's a hard world out there for actors. Choice parts like Gollum and Gandalf don't come down the road every day. My bet is that both men would return to reprise their roles -- with Jackson's blessing.