You are still assuming a lot of things.
You have no clear idea of how much 2in1 sell collectively... And regardless things are changing with the move to ARM.
The heat and weight you mention is something that can precisely be addressed by the move to ARM.
Extremely poor software is something I disagree with. Windows is garbage on Macrumors where everyone prefers a Mac. In the world as a whole, tons of people prefer Windows to MacOS (I for one do).
Pencil support is bad is just false. EMR tablets have excellent pen support, latency is as good as Apple pencil and there is ton of software that can take advatange of it. And MPP has improved a lot and is now a very decent option.
And what a tablet is, is different from person to person. If you want a stylus to take notes or annotate or draw and want to watch youtube etc. and don't care about apps (that's my case), I can see a Windows tablet like the Surface go with a Snapdragon X chip to be a great iPad (the 10.9/11" size) replacement with much better file management and support for software that the iPad does not support.
I do have an idea about how those 2 in 1 things sell - they sell so well that all of the manufacturers had to enter a partnership in order to have any chance taking on Apple's MacOS + iPad range. There's statistics published quarterly, it's not a secret that things were not going so well.
Windows being garbage has nothing to do with the forum platform you're discussing it on, it's objectively flawed, inefficient, non-secure, non-flexible and unreliable in actual, measurable ways. All you need to do is grab it in your hands, pay attention and understand what's going on here.
Just about every other popular OS is way ahead of it by today's standards.
People use it because they often have no other choice or don't know any better - Microsoft has dug itself deep in several sectors (through very questionable practices, no less) and positioned itself to deliver on quantity, not quality.
And Microsoft knows that very well, they tried refactoring core services and essentially gave up, now they're just slapping on band-aid after band-aid, hoping that people don't notice and that it doesn't fall apart. Now they're trying a 2nd attempt at ARM after failing miserably the first time around, and I'd not be surprised if it's as half-assed of an effort as it was before. Apple at least had the conviction to make a difficult call and commit to it 100%.
The un-docked surface will not come anywhere close to being a tablet comparable to the UX you get on an iPad, it will once again take the first round of people to burn themselves believing it can, only to realize it's heavy, badly optimized and ultimately unusable. To have a good tablet - and you know, use it with your hands only - you need a touch-first OS, which Windows is not. They tried with Windows 8 and failed miserably.
And the pencil - please, I've tried all sorts of these windows machines that seemingly support it and none of them come close to the low latency, responsiveness and functionality you get on an IPP.
Microsoft will try to lure in some quick cash by milking the AI buzzwords and then probably side-line ARM development once again, because they lack conviction and talent to actually bring any innovation.
So, go AI PCs!!