I still think that Hayter is involved and/or is playing Snake, but my reasons are split.
On one hand, being a fan of the series for over a decade now, it's hard to think of a MGS game without him. He is Snake. Part of me doesn't want to accept that Kojima's vision may be that Snake should be voiced by someone else, even if that someone is a talented movie/tv star like Sutherland.
On the other hand, I still don't see why Hayter couldn't voice future projects that involved Solid Snake, like an apparent remake, or re-imagining of the original MSX Metal Gear games. Kojima hasn't really pidgenholed himself into saying that Hayter is out forever, or that Sutherland is the official voice of both Snakes now. Not to mention I'd find it pretty fishy that Hayter keeps involving himself in this. I understand times are a lot different, what with twitter offering a 24/7 soundboard, but Hayter comes off as pretty professional. He's in the movie business as well, he's not really hurting for work and I really don't think he'd keep twisting the knife about this game unless there was more to this than we know, especially given how much he seems to enjoy the series and the fans. That's all speculation of course.
I don't know. Maybe it's all just being hopeful on my part. It's hard to see a change like this, especially when it could be seen as unnecessary to most. Still, Kojima is known for bucking trends. He always has, and likely always will. The brilliant switch at the beginning of MGS 2 is still one of the greatest twists of all time, and added a lot of deeper meaning to that game, whether you realized it or not. I respect Kojima's vision. I'm not going to try and get some sort of petition for Hayter to come back, because at that point it feels like it's no longer art, but just a service for fans. I just hope this all turns out for the best, and I hope we do get to hear Solid Snake again, one way or another.