I think you're foolish to imagine that MS won't use this to their advantage. Right now I'm sticking with 98 for my MS OS because I don't feel that microsoft has released a better os yet. 2000 might be dandy but I can't afford enough ram to make it speedy right now. I think its a few years off, but eventually when for some reason or another when almost all ms users will be using registered software, ms will use that to make money.
"Ohh yeah, we're very sorry but your one year lease on that ms product has expired and we are no longer renewing that product. Could I interest you in our new Spyware 3000 OS though? Yes ma'am that is your only option if you want a MS OS"
Its a pretty simple way to force upgrades in the future I think.