Rand's end

not only he wont retire but he will lose the ability to channel once the last battle is finished

Why would this happen? I mean it is not like channelers loose their abilities left and right it would mean he either had to be severed by someone or burn himself out at some point. I guess that could happen but since it is rather devastating for channelers to loose their abilities that will not be a good outcome for the guy, it do not seam likely that the main character will end up a depressed wreck at the end of the books, I doubt this will be the case.