This mentality is around because of the amount of work required to transition away from x86. So much code would need to be recompiled, no longer would I be able to load up Half-Life that came out in the 90's and it just work flawlessly.
If it was strickly assembly language programs, then yes, I understand perfectly the issue. But these days, there are many layers and tools that can help on that part.
Or at least, the reason I wouldn't want x86 to go anywhere anytime soon is because having that compatibility with everything is simply awesome.
Trust me, so do I. but at the same time, as mentioned above, there are options and tools, something like Rosetta or WOW can help.
Apple control the entire environment in their walled garden, so its much easier for them to transition to ARM, since they themselves have to put all the work in to recode everything and convince developers to spend time doing the same.
they have done something good with their rosetta tool, but they dont really care for backward compatibility as much as we do.
I'm not saying it's impossible for ARM's architecture to become the defacto, but I don't think it'll happen without a very good backwards compatibility layer or there's a very long transition period, where games and professional software is released simultaneously on ARM and x86 based systems for 20 years and eventually x86 versions stop being made.
Hence why I said "potential" and why I said "technology moves forward" sometimes, you simply have to start anew.
Except for certain programs here and there, that requires absolute top performance from the computer itself, in the future, maybe ARM will simply be fast enough to emulate those old programs.
Example, look at how a Raspberry Pi can run pretty much everything made for the 8 and 16 bits computers.
If you look at the transition between 32-bit and 64-bit versions of Windows though, Microsoft still release 32-bit versions of Windows 10 and the latest Office versions.
MS main selling point is indeed backward compatibility and even them have remove some of it, for example, on 64 bit windows, you cant run 16 bit code.
But then you have something like DOSBox that does allows you to do that.
Again, I'm talking the future, since as of right now, this is simply a slow transition and as I also said, depending in the fact that Intel or AMD can move X86 to the same power levels as ARM, then they can continue to exist.
Then again, all you need is a good lie to kill a product, see how Intel killed off the mighty Alpha and HP PA-RISC with lies about how good Itanium was going to be.
Edit forgot to add, remember VirtualPC on PPC Macs? that thing ran x86 code on a PPC CPU. Imagine something like that, but on ARM or RISC-V.