Well, when you mention a live action movie, I'm sure Keanu all crossed our minds, even if you didn't actually want him to take the role. If nothing else, his involvement will probably help it toward completion. I think it would be cool if he could get Spike's body language down which I think is a big part of the character and I think Keanu could pull it off with his lean body.
We'll see, I think there are so many aspects of the anime that will be hard to capture that this is only the start of what could go wrong but if they could get close at all this could be a really cool movie.
Adrian Brody as Spike
That's an interesting choice, I could picture that though I'm not sure if he's ever done a similar role.