The death of the PC is overrated. Tablets aren't going to run your IDEs soon enough and don't even try to argue that you code on Macs.
Not everyone wants to run their web services off the big cloud providers either and you need PC parts to run servers right now. Even Amazon and Google need PC motherboards.
The last thing is everyone threw code optimization out of the window and the ARM or MIPS architecture though powerful don't go well with the bloat that permeates the IT industries today.