I agree with 2 points here:-
The first is that yes, my initial reaction watching SPECTRE at the cinema was that they left the ending to leave it open for a Craig return or a new actor. I've always believed that. I also said way back in 2008 that Daniel Craig would leave after 3 movies, and I was shot down at the time, and even though I was proved wrong, as he's done another one, I wouldn't be surprised if now is the time.
The second point is that if they announce a new distributor and a huge amount of money became available and they got Daniel back and announced it was going to be his spectacular last hurrah, I know there would be excitement, and I know I would love it!