The problem is that if he was to leave now, a lot of what happened within the film between Bond and Oberhauser (Waltz's character) would have been pointless as we had no real ending to it. In a way we kinda did, though if that was the ending of it, it would be a tad disappointing. I'd still be fine with him leaving if he wanted to. Though I would like to see just one more.
For anyone who doesnt want to know anything -SPOILER ALERT....DO NOT READ ON I 100% genuinely thought when he first really appeared "Ah, Waltz is trying to act a bit like Donald Pleasence", And then of course it became abundantly clear why but it was as if he'd tried to copy him. Made it a bit weird to watch. I also always think he talks like Woody Allen, it's a bit off putting when he's trying to be an evil megalomaniac.
I think they're saving him for the next film to be honest, which if Craig isn't going to be around for, is a massive mistake and makes the majority of Spectre pointless. The problem is if he is the main villain in the next one, they are going to have to do another escape along the lines of Skyfall, which is too fresh in the mind (as was a copy of another superb film, The Dark Knight)
