It's a bit of a poisoned chalice for someone outside of Microsoft as if Gates and Balmer remain on the board as any new CEO will be continually undermined by people "going to Bill/Steve". To appointment someone from inside Microsoft is simply rearranging the deck chairs.

Best thing for Microsoft would be to hire an outsider who will come in with an unbiased eye and clear out the deadwood to give new growth a chance or to milk the cash cows to their inevitable conclusions. To be able to do this you need Bill and Steve and their old guard out of the way.