If tablets will really go mainstream, then their price will hit rock-bottom faster than you can click on a Metro tile anyway. By the way, what are you saying? That manufacturers will just stop producing PCs and laptops? That's like saying car companies will only produce sports cars now, because they are cooler and more costly.
I must admit I am somewhat impressed by how fast MS was able to cripple Windows to such extend. Three years is not such a long time for this, not even in IT.
So if the tablet- and touch hypes wane, maybe MS can de-cripple it in record time, too.