IBM is the master of the pay-as-you-go model in the enterprise.
Microsoft is not, and has never been, a major player in the enterprise.
Microsoft makes consumer-grade software.
IBM doesn't even try to push pay-as-you-go to the corporate desktop because it's a loser. One size does not fit all when it comes to the end user.
But that won't stop Microsoft. They'll plow headlong into this idea that they can get back control of every desktop PC.
The thought of being paid every month for the same software simply has too much of an attraction for the bean counters at One Microsoft Way.
They may try to ‘force’ the market down this road. If they do it will fail, and you’ll see a tech revolt that will make the Vista uprising look like a typical day on Jerry Springer.
Developers and consumers will sour to their new ‘platform’, particularly the developers if it requires a full code rework. And with most of the open source OS’s supporting Windows binaries in some form or fashion, people could flock away in droves.