Interesting idea, but don't think the demand is there for Windows DAWs in all form factors.
In fact, according to this MS article, development for PC desktop Win32 is still possible using the new platform. So it is possible to use modern tools and continue development without falling behind. It's simply what device family API's you target your app for. So using the same codebase, you can target smaller form factors (or not) as you wish.
https://msdn.microsoft.com/en-us/windows/uwp/get-started/universal-application-platform-guide A good comparison can be made with Apple. Even though there seems to be an active music app and device ecosystem growing up around the iPad and iOS, that is still a distinct OS from the desktop MacOSX. But even Android doesn't seem to be keeping up there. So where is the demand for Windows devices going to come from?