Microsoft still gets their money so why would they care? This actually opens up a new market opportunity for them.
If you're going to say it makes it easier for people to switch, I don't see that since dual booting is not a normal user process, usually only geeks do that.
This is more for those that want to run games and other software that isn't available for Mac, so chances of them completely switching is low.
It will allow Mac users to run Windows games, but Apple is targeting Boot Camp to both professional and home users. The top story at the Wall Street Journal web site right now is an interview with Apple's VP Phil Schiller -
"Running Windows on a Mac could appeal to professional users who want to purchase Macs for their homes but don't because they need to run a corporate application that operates only on Windows, he said. Then there are consumers who are interested in Macs "but want the safety net of, 'If it doesn't work out I can run Windows,'" Mr. Schiller said.
This is a brilliant strategy for Apple to win customers who want to try a Mac while preserving their investment in Windows software. Those folks can eventually dump Microsoft products after a gradual transition to the superior Mac OS X system.