Of course it'll happen. The market has reached saturation in mature markets and the money well is about to dry up. Everyone is looking for the next things, apple, Samsung, amazon, and MS. They want that adoption phase technology that consumers drool over.
If smartphones were the eternal be all and end all, why would every major company involved in them be making massive investments in future tech?
It won't.
The market has reached saturation and STILL it doesn't want Windows Phone offerings. Everyone is looking at the "next big thing" but there's one very common thread there: it will NOT run Windows. It will run Android (well, Apple is excluded because Apple doesn't innovate, they only do things other have done first and slap an Apple logo in it).
Well "apps" are designed for touch only, and UI for a small screen. The moment the form factor or primary input method changes, a back catalogue of apps becomes less useful than win32s on a phone. It's a limited life modality, that's locked to the specific hardware platform its run on. This would be like claiming that mouse and big screen applications on PC, meant that windows had dominance eternal in technology.
The nature of technology is forever changing. The iPhone itself was invented on the back of a "let's wait for the next thing' strategy after mac/OSX nearly sunk apple.
I can't see what chance android has for catching up with PC. Their development funding model doesn't support the depth of software, their OS isn't designed for it at any level. Far easier to scale down, than scale up. Take away detail, than create detail. Google would have to code everything themselves. And they seem to be making no real attempt at it either.
Although I doubt I have convinced you, of technologies limited life, as someone who seems to believe that slab phones will reign supreme for a long time.
However consider that this market has been around for how long - ten years. Ten years from massive adoption, to saturation. Ten years to shift the balance of power in the OS world, and profit margins away from the desktop. And all from the release of a new form factor, which at the time, had no apps.
Rarely have we gone ten years in the last 100 without the introduction of some paradigm changing piece of tech.
First of all, you don't seem to understand what an app is.
And
app is an application you get from a dedicated OS store. As opposed to a
program which is an application you get via a disc, a digital code or directly from the developer.
Traditionally, programs are what run on Windows (.exe, x86, Win32 etc), apps are what run on mobile devices (phones, tablets etc)
So, when they say that "apps are the future", they mean that the paradigm of you buying the programs from wherever you please will go away and you'll be locked into OS "Stores" like the Google Play Store or the Windows Store or whatever Apple calls their store.
With that distinction in mind:
1 - Most apps are actually not designed for touch only and also not for a small screen. If you look for example at Google's Material Design guidelines, they don't prescribe anything for "touch only".
Which is why you can connect a phone to a display and use them with a mouse.
Then there are apps which, of course, are only designed with touch in mind. Things like Instagram, Snapchat etc are NOT meant to be used with a mouse and a keyboard (which most people don't use anymore, anyway). You just need to use the Windows Instagram app on a PC and you'll see how absolutely pointless it is. You might as well open Instagram on a browser and it will be as useful.
2 - Windows doesn't need to leave Win32 programs behind. What makes a Win32 program unusable on a mobile device is its design. If a developer changes the design of the program, you pretty much have that usability problem solved.
Things like Project Centennial are NOT about making sure Windows programs start running on different for factors. They just aim at putting the existing .exe programs in the Windows Store so that Microsoft can rob the developer of 30% of the sale price of the program. If tomorrow Google placed Chrome on the Windows Store, they wouldn't change a single thing about it. You'd be downloading exactly the same installation file that you currently download directly from Google, but it would be coming through the Windows Store. Which means Google would have to submit any update to the Windows Store instead of updating the program directly etc. Cumbersome and pointless.
3 - You completely ignored that personal computing has been around for well over 25 years. It took 10 years for Android to surpass Windows. But it took 30 years for phones to surpass computers. The so called "paradigm shift" from fixed computing to mobile computing took many many decades to happen. It didn't happen with the iPhone nor just in the last 10 years.
The iPhone brought no innovation to the table. What the iPhone offered wasn't new nor revolutionary. Everything in it already existed. Apple just packaged it in a pretty case. Which is what Apple does. They don't innovate, they market things properly. You'll see that clearly when they introduce wireless charging on their phones. We've had it for 5 years, but they'll make it seem like something new and innovative.
4 - And as you pointed out, when the iPhone came out, it didn't have apps. Jobs said it would all be done through the browser. Well, then apps cam in and no one wants to use the browser to do things that can be done via a dedicated app (just look at how clamorously the attempt of Windows Phone to make web-wrappers a thing failed.)
And Android HAS the apps. All that Google needs to do is to make a push for developers to make sure their apps scale well and developers WILL do it. Because unlike Windows developers, Android developers HAVE a reason to make sure their apps work well on any screen.
Google hasn't made that push so far, and that's why Microsoft is trying to rush and attempt to convince developers to stop making Windows programs and start doing proper UWP apps. So far those efforts have failed. And if Google makes that push (and sooner or later, they will), then Microsoft is in big big trouble. And there's no "panorama shift" to help them not be.
And all of this brings me back to the topic we were discussing:
Nokia will NOT be making Windows products (specially not mobile ones) going forward. Because neither the current nor the future market will be based on Windows. It will be based on Android. Microsoft itself knows that, which is why they're all in on having their services on Android. If anything, the next "paradigm shift" will be the inversion of the status quo. Currently you had Google needing Windows to keep Chrome and their services alive. In the near future, you'll likely have the other way around: Microsoft needing Android to keep their Office and other software alive.
And Nokia will already be on the right side of the future of mobile computing.