I know this may not be the right forum but I don't think the PC is going to die any time soon. Sure, maybe there might come one day where the difference in absolute performance of a portable device and a stationary device will not have much impact on an average end-user.
But let's look at Hi-Fi equipment that has evolved for a considerably longer time than PCs and where you in fact can get pretty decent stuff even in smaller form-factors since at least the early '90s. Do we still have separate-stage Hi-Fi gear? Yes. Do we still have standardized rack-mounted equipment aimed at professionals? Yes we do, in fact even at price-points that are affordable to a more humble consumer. In fact there still is to this date Hi-Fi equipment available in all thinkable shapes and sizes for a rather wide consumer population.
The desktop PC is a little different because it is more based on standard specifications such as the PCI-SIG, USB, Ethernet, AT (S-ATA, ATX etc), SCSI, ... standards. That has paved the way for whiteboxing and customization like little kids build and play with LEGO. We still have LEGO, don't we? Anyone who had the joy of playing with LEGO ought to understand the joy with building and customizing a rig for your own needs. The release of the Raspberry Pi and other small form-factors boards suggest that a wider range of consumer needs will be catered for.
So no, I think the PC is going to stay for quite a while.