Patents may be selectively enforced, there's no forfeiture as there is with trademarks.

Intel had (and has) no issue with qemu or bochs emulating everything, as long as they were niche and/or promoting the Intel platform (and grudgingly accepting compatibles).

However a move to rid Microsoft's platform from Intel altogether without compromising compatibility is something worth fighting for. I heard that ARM is rather similar in that aspect: emulators for development are a-ok, but trying to run ARM emulation on a consumer product with no ARM components inside will drive up the legal fees until some licensing agreement is set up.

Intel uses that for their x86 Android devices - and as far as I know, ARM did not sue.

Intel also makes arm processors (a cortex a5 i think?); perhaps they do license it.

Licenses can be revoked, patents cannot other than by analysis and finding them invalid.

As soon as Intel licenses the ARM ISA for each device, ARM Ltd. probably doesn't care if it's implemented in silicon, software or expressive dance.

We are talking about patents.