I would assume, there are always people who gets tiered to use one or other product or device. There could be always chance for MS to get increasing attention on the market (theoretical). Since now-days MS phones are pretty rear/unique, which gives them
additional value. It is not easy to buy one, you know!
I've recently bought my "new" MS phone, that works great even with continuum (and it is so cool), there is only some thousands of all around the word! (Szilard would probably tell us some nice metaphor about this like to buy BMW or Mercedes versus Bugatti,
but he may select makes more carefully I assume)
And yes, my phone is pretty much alive as long UWP-Apps are developed, which I assume will remain for a while, since UWP is essential part for Windows 10, Windows S on PC and on always connected devices. Even my Lumia 640 gets some new apps. Unless MS also
drops UWP and replaces it completely with Xamarin (again Szilard shell give us some metaphor)
Does someone know how many Alcatel idol 4 pro and/or Lumia 950 was produced in total? It would nice to see those information on wiki.
And yes, I'm almost sure we will see some future MS phone with some Windows variant. Or Lean phone with "Cloud Windows" or "Streaming Windows" who knows.