I think that is the point. I have a tablet for on the go. It is easier to carry than a laptop and has some additional functions that I use - e.g. Navigation. But I would never give up my PCs and live only on the tablet. Just imagine trying to do any serious video editing on the itty bitty screen, not to speak about the muscle the machine needs to do that conveniently.Seems more likely that many are buying portable things as well as using a proper machine.
I have a bunch of friends who do the same. But nobody would give up their 22" screens and the power of a desktop.