I've been hearing a lot of this recently: "You can't say the PC is dead, because 'smart' devices can't replace the power and functionality of the PC." That's a moot point, because it isn't what those systems are capable of that matters, it's what people actually want that matters, and the vast majority want smart devices (according to all the sales figures), regardless of whether they're less powerful/functional than PCs or not.
The market has spoken, and it doesn't want PCs.
Like it or not.
Personally I think this is a good thing, not because I have any particular objection to PCs (hardware), or even (selfishly) because I don't personally need them any more (in fact I'd be quite happy to keep using them), but because this may be the only way to finally break Microsoft's monopoly ... circumventing it by making the Windows delivery vehicle obsolete. No PCs = no Windows. It's really that simple.
This is an especially important consideration now we have the threat of "Secure Boot", which is destined to hard-wire the PC to Microsoft permanently, not just at the Point of Sale (as it has been up to now), but even after-market. That'll kill any alternatives (such as GNU/Linux) stone dead. It's already proving to be a difficulty, as a recent Linux Kernel mailing list "discussion" between Linus Torvalds and Matthew Garrett demonstrated.
But ironically, Microsoft's attempts to completely assimilate the PC have seriously backfired. For decades now, Microsoft's OEM "partners" have point-blank refused to offer their customers a choice of OS, and people are sick to death of this racket, but they never had much of an alternative. Macs are and have always been too expensive, and the only other option is to build your own PC, which is quite a daunting prospect for your typical, technophobic consumer, and isn't even possible at all with laptops.
But then, finally, there's an alternative totally beyond Microsoft's grasping clutches: "smart" devices running iOS or Android. Microsoft has no closed-shop of OEM "partners" to exclude alternatives from smart devices, it doesn't even have a viable OS to distribute on them, and what little it does have is totally incompatible with the ubiquitous Win32 API, the only thing tying anyone to Windows in the first place.
That is why people are abandoning the PC in their millions. Smart devices are currently the only (cheap and easy) way to get a computer without Windows, and that's especially important now we have the deeply unpopular Windows 8