He made an opinion and was attacked for misstating "facts", which he did not state. You are free to disagree with his opinion, of course. I, also, do not agree completely with his opinion. We don't know where Microsoft is heading. Or at least, I don't.
I can see, though, how one would feel that they are going towards subscription models for their products. They've taken the first step to do so with Office by offering subscriptions in addition to boxed copies: something they did not do years ago. On some platforms, such as the iPad, a subscription is requirement to have Office be anything other than a viewer only.
Again, no one said Microsoft is guaranteed to move to a subscription model for Windows. We don't know if they will or will not. It is possible, though, to interpret some of their recent moves and past philosophies in such a way such that it's a possible path for them to take.