Daniel Craig doesn't want to be James Bond anymore. Some have argued that his comments about slashing his wrists before playing the part again are really about using the press to negotiate a better deal for himself, but I take his words at face value. In fact, I'm not convinced he ever really wanted the role to begin with... that he was more interested in the potential exposure and interesting work opportunities being James Bond would afford him. Even at its best, his relationship with the character has been tepid.
And look, I get why he'd want to walk away: he's almost 48, and getting in shape must be harder each time around; whenever he goes out in public, he's mobbed by adoring (and obnoxious) fans - a real liability for an actor as private as he is; and word on the street is that Spectre isn't very good and was something of a troubled production. He's richer than God at this point, so who needs the headache?
It doesn't matter. Daniel Craig will return as James Bond for one more film because he's contractually obligated to. I'm honestly not sure why people keep discussing the matter as if it's up for discussion; it's been known since at least the release of Skyfall that Craig has a five-picture deal with EON, the production company that owns the film rights to the franchise. To date, he's been in four films. The math here is easy.
If Craig were to say "Nope. I'm outta here," that would be a pretty brazen breach of contract, making him liable for MILLIONS [Unless, of course, his contract has an escape hatch allowing him to walk away, which an agreement of this magnitude might.]
On the other side, EON isn't likely to release Craig from his contract - something they've done with prior Bond actors - because it would probably accompany a huge payout. Considering the astronomical amount of money at stake, letting Craig go at the height of his popularity doesn't make financial sense; it may actually be cheaper to force him to fulfill the agreement and get one more performance out of him than to pay him to leave and then pay a new actor on top of that to shoulder the film Craig was supposed to... in essence paying twice for one role.
The only way I see that happening is if their relationship grows so poisonous they simply cannot move forward together amicably (which may be what Craig is trying to accomplish with his horrible kvetching lately). That said, the terms of the deal are tightly guarded so no one other than the principals know exactly what's what.
So short of an official statement from EON announcing a split, expect a crabby 50-year old Craig to be doing press for Bond 25 in 2018 or 2019.
UPDATE: In a recent interview, long-time Bond film producer Michael G. Wilson stated that Daniel Craig has not been contracted for five films, despite rumors to the contrary, but thinks he'll return for a fifth film. So maybe Craig's complaints (which have noticeably dropped off in recent days) really are an effort at using the press to negotiate a better deal; actors do it all the time. Regardless of his motives, I'm inclined to think Craig will return for one more film, even if there's presently no deal in place.
There's the money, sure. But I think it's more a matter of pride and craft. I recently saw Spectre and thought it was good - not great - and the critical reviews have been all over the place. Some loved it and some hated it. I personally thought the script was under-baked (a similar issue plagued Quantum of Solace which was written during the WGA strike) and the editing was flabby, but ultimately I felt it was of a piece with the previous Craig films.
But no matter how you cut it, it's just not getting the same love as Skyfall, and you can see how that kind of response might make an actor's actor like Craig pause and think harder about his legacy in the franchise. Do you go out on a meh note or suit up once more and bring it home in spectacular fashion? I don't think he's excited about the prospect of suiting up again as Bond, but I think he could be persuaded if it gives him the opportunity to do something really special with the character one more time, and get it really right.
[Author's Note: While we're on the topic, let's squelch the Idris-Elba-as-next-James-Bond rumor too. If Craig fulfills his contractual mandate for one more Bond film, that means Bond 26 won't be coming out until 2021 at the earliest, when Elba will be 49. No matter how athletic and charismatic he is, EON won't want to build the next era of Bond films around an old guy. Sorry. Likewise for Damien Lewis, another intriguing, talented, and older actor who's name has been bandied about lately. Expect someone in their early 30's to be cast.]