These days "good enough" CPUs are cheap enough that they could probably field a generation of switchover machines which had both x86 and ARM processors and just build a virtual machine style environment into the OS to more or less seamlessly run the "legacy" apps on "legacy" hardware without the need for all of that software backward compatibility. Running old apps on a cheap i3 would be far better than trying to do x86-64 software emulation on ARM.

Of course, the business relationship side is not quite as clear as the technology side if you want to ensure consistent delivery of a lot of parts -- "sell us a bunch of CPUs for this machine designed as a stopgap until we don't need your CPUs anymore", though maybe that is solvable by dealing with AMD.

All that said... I'm perfectly happy with x86 on the desktop and have yet to see any indication that ARM can compete on the types of jobs I still do with "desktop"-class (whether they be actual desktops or laptops) machines, like code compiling, RAW photo editing, video editing, etc.

It is objectively cheaper.

ARM is better for <5W applications when performance is secondary to power consumption, but Intel is beating them at performance/watt ratio everywhere else.

The ARM ecosystem is objectively healthier than x86, due to competition from multiple vendors.