Not entirely his fault. Microsoft have been in the console business for over 20 years and have fuck all to show for it. Phil has done sweat F.A across the various positions he's had.
If microsoft left now, what would they leave behind? What difference would it make? Their main games are (were) Halo, Gears, Forza. One of those is pretty much dead at the moment, and a shadow of its former self, one no one cares about, and the last is a solid yet uninspired copy of a flagship game from a rival platform.
Xbox has been useless since 2009.