The PS4 has a number of exclusives e.g. Uncharted, Last Of Us, Little Big Planet which are system sellers. And if you think the PS4 is just a regular PC then are you missing a lot. The unified memory and asynchronous compute aspects are important differences from most home PCs.
The PC is the one that is likely to struggle since fewer and fewer people are buying desktop machines. And laptops/tablets are all about battery life.
Well I don't care enough about those to buy a PS4 just for them. And the PC has been dying since forever. I grant you that the unified memory, etc. is really nice, but as we've seen from e.g. the PS2 - how hard it is to program for a system doesn't really matter in the end. And the PC is not in any way hard to write programs for.
The PC is the one that is likely to struggle since fewer and fewer people are buying desktop machines. And laptops/tablets are all about battery life.