XP has 6 months life left, after that I suspect most 'enterprise' web app developers will drop support for IE9, I know we certainly will be.
Dropping IE 9 support isn't even on the horizon for me.
N.B. The company I work for sells to US k-12 schools.
IE9 was optional (users were presented with a dialog and they could decline installing it), while IE10 was automatic, no questions asked.
Alas, numbers of browser share say that this process is not working as smooth as MS would hope.