> So, on Windows, assuming Macs don't take away any more market share from Windows, they need to beat AMD+TSMC.
No. All it needs is
- Microsoft and Qualcomm breaking their unholy and IMHO questionably legal alliance
- an ARM CPU vendor willing to do the same as Apple did and add support for accelerating translation of x86 code (IIRC, memory access models/barriers are done differently between x86 and ARM, and Apple simply extended their cores to be able to use the same memory access/barrier model as x86 on translated-x86 threads)
- an ARM CPU vendor willing to implement basic functionality like PCIe actually according to spec - even the Raspberry Pi which is the closest you can get to a mass market general-purpose ARM computer has that broken [1]
- someone (tm) willing to define a common standard of bootup sequence/standard feature set. Might be possible that UEFI fills the role; the current ARM bootloaders are a hot mess compared to the old and tried BIOS/boot sector x86 approach, and most (!) ARM CPUs/BSPs aren't exactly built with "the hardware attached to the chips may change at will" in mind.
Rosetta isn't patented to my knowledge, absolutely nothing is stopping Microsoft from doing the same as part of Windows.
[1] https://www.hackster.io/news/jeff-geerling-shows-off-an-amd-...