there are 3 flaws to the argument the the PC is over for most users.
1- offices will continue to use PC for they won’t want their employees using their own tablets with “who-knows-what-software(malware)” on it. And there is zero advantage in using tablets. Actually what will likely happen is one PC/server will service multiple users, each with their own monitor, etc. And offices are still going to be a plenty for some time.
2- virtual worlds will increasingly become more popular not only for entertainment but also for communication, it’ll gradually become more worthwhile to meet online then offline. And that will continue to require the greatest performance available for quite some time.
3- the upcoming rise of A.I.s and distributed computing (I.E. for large projects), lending/selling/donating computing cycles; will basically mean: the better processing-power/price ratio the better, no matter what the individual processing-power requirements are.