Yes, but large parts of the world are explicitly trying to avoid becoming dependent on MS software. While Windows is still growing in other countries, quite a few are subsidizing or requiring the use of other OSes (usually linux), trying to avoid too much lock-in. [Added: OK, I see what you are getting at, I had read the original paper to mean that Windows on PCs was at a plateau; it is pretty common to use PC to mean a PC with Windows. And with iPads, netbooks, smart phones and the like, the PC form factor might actually be at a plateau itself, or approaching one.]