Maladies of x86 cpu's
The fall in PC sale can be directly attributed to the customer disdain of Microsoft products, which are only going to continue the downward path of PC sales with the idea that the mobile/tablet inter-phase is the way to go. The use of a PC in the commercial sector where the only bastion of PC's is left does not want or require a shopping site OS. a tablet inter-phase or calling programs apps. All the modern OS is doing is chasing a market which left M/S OS systems 5 to 6 years ago and is not going to go back. This reminds me of the 1980's and early 1990's when the accounting machine giant refused to believe that their market had flown. Intel,AMD. and M/S. are now the next ones to fell what it was like for Burroughs, Wang etc.
The rise of a cloud O/S is not helping either.
The only consumer sales will soon be the PC Gaming high end market, design cad etc.