PCs are not coming back in the sense that they won't see growth like they used to, but at the same time they're not going away. To be fair, most people don't actually need a PC. My wife uses a Nexus 7 as her main computing device, and loves it (she prefers it to a PC).

As an aside, Chrome OS devices are gaining alot of traction... Probably because they're more than adequate for most people's needs as is, and developers can always switch on development mode for a full set of Linux-y features...