There was a recent tweet from Brian Bendis that his books will be taken care of. Assuming we're not talking about mob style euphemisms, that suggests we need replacement writers for his books. So who would be a good fit? I'll list the books, but I only really have an idea for one right now:
Defenders - I heard someone else suggest David Walker for this and I agree completely. I think he'd be a great fit. While Bendis's writing feels more serious than Walker's, it also felt like Defenders was trying to fit in some quirky, off-beat humor into moments, which fits Walker's style perfectly. Plus, as a writer of both Luke Cage and Iron Fist, he has experience with the characters.
Invincible Iron Man - It feels like Bendis's run will end with a new status quo with Tony Stark (although, hopefully, with Riri there as well). I'll try and give some thought about this and come up with a suggestion. I think they can take it in any direction they want, so this doesn't need to be a direct continuation.
Jessica Jones - I would ideally like a female writer who can go into dark characters to write this. I wouldn't want someone whose instincts are to go light. So no Mark Waid or Dennis Hopeless, although both are incredibly talented. Maybe someone from the indie world could be convinced to give it a shot?
Spider-Man - Again, I'm not entirely sure. I think G. Willow Wilson would do a good job given that she knows how to write a socially conscious book about a teenage superhero figuring out his or her place in the world. That being said, she obviously has much more personal experience with the world of Ms. Marvel, so it would depend on how comfortable she would feel writing a character with a very different background. Also, whether she wants to get typecast or not.
Those are my tentative thoughts, what are yours?