Microsoft to make Windows 10 free to Windows 7, 8.1 and Windows Phone 8.1 users | ZDNet

[Mike O'Dell]

from a corporate standpoint,
the vast majority of the revenue has come from the Office
products and supporting server products quite some time.
when Microsoft announced the Mac version of Office, 
they made the point that the new code base from that
would be the baseline of Office to make sure that
the versions maintain complete internal compatibility.
and now they've even launched an iOS version.

the more interesting question is what will they charge
for WinTenTen if you don't have an earlier version.
If that is cheap enough, or even better, BUNDLE it with
Office, they might sell a bunch of Office to Linux users.

I think MS would be *delighted* if they simply slow
the rate of erosion.

    -mo