This announcement provides a bit of credibility to the suspicion that Microsoft has been wanting to make a "Surface Phone" device for some time, but was delaying until the right pieces were in place. It is possible they had been working with Intel's Broxton and that chip's cancellation required returning to the drawing board, so to speak.
But it seems likely, to my mind, that what we see today—x86 emulation on a Snapdragon—materialized because Microsoft wants to deliver full Windows 10 on a phone-sized device and Intel wasn't able to give them the necessary platform.
Emulation may be inelegant, but the video [1] confirms performance that would be "good enough" (oh how I hate that phrase) for many users.
If it works, how usable would a desktop app run on a phone? I think Microsoft would intend to do this for tablets (which need longer battery life than what Intel provides) rather than a Surface Phone.
A desktop app would probably be tricky to use on a phone screen, but the big idea here is that you can connect the tiny computer in your pocket to a TV or a monitor and have it work just like a laptop, with no OS restrictions.
But it seems likely, to my mind, that what we see today—x86 emulation on a Snapdragon—materialized because Microsoft wants to deliver full Windows 10 on a phone-sized device and Intel wasn't able to give them the necessary platform.
Emulation may be inelegant, but the video [1] confirms performance that would be "good enough" (oh how I hate that phrase) for many users.
[1] https://www.youtube.com/watch?v=A_GlGglbu1U