Microsoft has spent three years just trying to figure out how to make some of its applications available through the cloud without ticking off its resellers so much they pitch competing products instead of Microsoft's and put Microsoft out of business.
Three years, going on four! That's a long time in the computer business if you're doing something that doesn't involve overcoming or avoiding limitations to the laws of physics.
I don't doubt Microsoft and every other vendor will fight just as hard to keep up with the times technologically without changing its business model enough to make the technology practical.
The other drawback would be half commitments from other vendors and end users, who might like the concept of total portability, but not the realities, which involve a lot of trust in employees and support of things they don't really understand and the confidence that as long as they can identify the really critical points of failure and protect those, that the rest of the system will adapt around them.
Just as in the early days of server virtualization and every day in cloud computing, that reluctance to trust or believe in the existence of something you can't put your finger on and poke to see it jiggle will hold back the evolution toward the creation of an actual operating environment for end users – a desktop without a desktop, a PC without the PC.
It's hard to believe in even understanding how all the pieces could fit together. For those who see personal benefit or loss in warping or limiting the concept so it's not really an envelope of software and networks containing everything the user needs, it never will be.
Microsoft has been one of the main forces preventing it until recently. It's been driven by users rushing into the cloud and virtualizing everything in sight and doing mission-critical things on every phone except those made by Microsoft.
It's been driven to the point that it is adding a whole series of functions into its main product that will make at least half that product completely irrelevant while still hoping to make money on it.
It should be possible, even for Microsoft. End users don't really care if the operating system can find the hard drive anyway.
As long as it can find the documents and music and movies and networks and it all runs fast without any fuss or too much mucking around with configurations and drivers and carburetors or whatever it is all those IT people drone on about all the time, the only thing they care about is whether "the computer" has the things they need. Not what bits of metal and silicon it has to talk into bringing them along.