no doubt - if ms wasn't there, someone else would be
as for them trying to reach a new base with each OS, i don't see it that way
they simply want more money from the same customers that bought their last OS
in fact, ms, the CPU manufacturers, and the computer manufacturers all do it in harmony
i suspect there is a lot of money involved when large companies upgrade
and - quite often, they may be forced to do so if they want to use the latest s/w and have support