Re: "Post-PC Era"
I don't think the return you imagine is necessarily going to happen.
It's uncontroversial to say that for some people a tablet is a better device than a desktop/laptop. Those people will migrate one way and then not migrate back the other. So I guess the disagreement is: how many people is that
I'd argue that it's a big number, being a large proportion of those that use a computer primarily for accessing the Internet. I further think that the people that just want to access the Internet are the reason that laptops have made their way into shops like Tesco, and that the £300 Tesco-level laptop is responsible for large volumes because it's so easily available and cheap enough compared to its perceived value to be an impulse buy.
So while businesses — not just technological but anything that involves document preparation or significant digital editing or anything like that, being pretty much all of them — and enthusiasts aren't going to migrate permanently to a tablet, a huge chunk of people are.