It might give a small boost to Windows-on-ARM that Microsoft has been trying for over a decade. Porting a typical windows app might be easier than porting to Mac/Linux because you still have DirectX and all the Windows libraries.
There's also x86 emulation on ARM. It's slow, but it might be enough to run that 20 year old business app.
Windows ARM seems to be a bit faster than that running x86. An older video showed pretty good performance: https://www.youtube.com/watch?v=DRBMBkL7SCM . Using an abstraction layer to convert system library calls to call native ARM system libraries instead so you don't have to emulate x86 versions of the system libraries.
This is the same concept box86 implements on Linux. https://github.com/ptitSeb/box86 . It's good enough to run lower end Linux games on a Raspberry Pi 4
Wasn't Intel saber-rattling about patent lawsuits when Microsoft announced that Windows for ARM would run some x86 apps via emulation? [1]
While I don't know what became of that, I can see Microsoft working out a deal with Intel because Windows is still huge on x86 and wasn't going anywhere.
On the other hand, if Apple is planning to completely drop Intel in favor of ARM and wants to implement x86 emulation, I can't see Intel letting OSX ARM emulate x86 without some form of resistance.
But what IP would be violated for x86 emulation? It's clear that Intel only threaten chipmaker who tried to add x86-emulation-acceleration ISA to the silicon. x86 ISA is complete 17 years ago, which mean a lot of patents has been expired today.
There's also x86 emulation on ARM. It's slow, but it might be enough to run that 20 year old business app.