Design and education kept Apple alive through the dark years. I can see gaming doing the same for the PC industry through the dark years of Cloud ("Mainframe 2.0") until "PC 2.0" arrives.
don't worry about PC itself, all offices around the world will make sure this won't die soon even if all gaming went bust. Heck, even myself at home, I haven't yet met a good enough replacement of my do-it-all-super-fast desktop back home.
True but that won't keep the high end alive. You don't need a very powerful machine to do office stuff. Gaming will keep the "performance PC" alive until a few more years of Moore's Law and people start realizing that these high-end gaming PCs with neonz can run the same sorts of "big data" work loads you can presently only really run in the cloud. In 5-10 years a sub-$2000 performance PC will have 8TB of PCI-X flash, 16 CPU cores, umpteen gazillion GPU cores, and 128GB of RAM, and "wait why do I need Amazon Cloud when I can have it on my desk at 0ms latency?"
Sure, there is a real comfort to work when you have big screens and a mouse/keyboard, but you don't actually need a PC for that, a tablet is enough.
Right now, PC are still way cheaper and the difference in power is still sensible, but I think this will change very quickly.
Of course, this is true for basic office work : if you need power, as a dev/graphist/whatever, a PC will still be the way to go.
However, most office job don't actually need that much power, and the flexibility offered by a tablet is huge : being able to work from anywhere, bringing your whole computer to take notes/read mails during a reunion, etc...
I meant you don't really need the power of a PC to work with a big screen : a tablet has/will have enough power to handle it, all you need is a dock for your tablet and and a cable between the big screen and the tablet. Same goes with keyboard.
The upside of a tablet is that while you can dock it and have basically the same comfort you have with a regular PC (minus raw power), you can also unplug it and use it pretty much anywhere.