It's odd to me that so many on here are talking about Davis potentially becoming Cook's replacement, when they are clearly such different players. Cook has far better acceleration, and speed, while still being able to bounce off a defender, and stay on his feet. Davis does have reliable hands, but his speed in the secondary would take a lot of plays off the table, IMO. He's a great #2, RB, with the kind of down-hill, bruising running style the Bills need, but I have a hard time envisioning him as a feature back.
But here's the thing, if the Bills already have a replacement for Cook in mind, it's got to be the newly re-signed Ty Johnson, IMO. Cook made some great plays in the red zone last season, but so did Ty. Ty Johnson has consistently made absolutely eye-popping catches, and has shown incredible clutch efficiency, situational awareness, and proprioception, and he may even be a hair faster than Cook. He's put up highlight reel plays enough times to know it's not a fluke. He has the ability to help keep a play alive when it breaks down (an important skill for the Bills' offense). And perhaps equally important, he has trust, and chemistry with Josh Allen-- you can't overstate the importance of that.
If tomorrow Brandon Beane said that they were moving on from James Cook, I'b be disappointed, but I wouldn't be worried about "who would replace his production," as another poster wondered. And, if in the next breath, Beane said that Ty Johnson would be the #1 for '25, my first thoughts would be, "... I can't wait to see that!"