I don't think he's Roxas, and he's not dead yet. I still say the old guy ISN'T Xehanort. There is no proof besides a similar costume, and if similar costume made it the same person all of Organization XIII would be clones.
I think that's him before he loses his memory.
I disagree that the old guy is Xehanort, I think the brown haired guy is. His eyes turn yellow, so you have that covered... The one guy does look like Roxas, but I don't think he is exactly.