I kind of disagree here. Compilers reached commodity status a long time ago. Nobody makes money off them compared to how it was in the 90s and the list of ex-compiler makers is as long as your arm (Watcom, Metrowerks etc).

'clang' is probably approaching the point that its good enough so the question for Microsoft is do they still see any value in continuing the develop their own compiler or should they just switch to 'clang' ?

I think this is the big shift we are seeing in MS this year. Instead trying to owning everything, they seem to be shifting their focus to owning the parts that have value and commoditizing the rest. The strategy was successful for Apple so its unsurprising that Microsoft is looking to a similar strategy as part of their salvation.