Linux will not counter. The question is if someone is willing to use Linux to counter. Microsoft is betting everything on this and banking on their desktop monopoly and name recognition to push them into a position of dominance.

And what, force everyone to a single desktop environment? It doesn't work like that in the slightest.

This seems to be a common thread for users coming from Windows/OS X who are baffled at the notion that an OS can exist with multiple replacements for the same part that all operate differently, and grows without a single company at the helm deciding how it grows. And the very nature under which most Open Source software is under encourages such diverse development. Short of snatching the rights out from under them you can't corral people and force them down the One True Path (which doesn't exist.)