Personally, I think they'd be better off doing an 'Apple'. They could use an open-source OS as a foundation instead of spending lots of resources going-alone with something idiosyncratic that's not used by anyone else. The resources freed up could be concentrated on improving the GUI environment (as Apple did) which is what 99.9% of your clients will be interfacing with.
But MSFT will never do this, they have the NIH mentality so deeply ingrained that they would rather die than look outside the MSFT World.
You never know. I feel as though we are going to see Microsoft one day implement a strategy that could go two different ways:
1) They end up giving away Windows for free (which they kind of announced with Windows 10). Windows 10 will be a free upgrade to everyone, including pirated users of Windows 8.
2) Windows moves to a subscription based model like Adobe's Creative Cloud. Instead of paying for a copy that you own forever, Microsoft allow you to create an account and sign up for a Windows account for X amount of time. Similar again to Adobe the cost depends on whether you commit to a full year or not.
There are definitely some interesting things happening at Microsoft, some that 10 years ago people would have laughed at you if you predicted them. Who would have thought that we would see an ability to work with Visual Studio on a Mac? Not me.
But MSFT will never do this, they have the NIH mentality so deeply ingrained that they would rather die than look outside the MSFT World.