Microsoft shouldn't get too much credit for maintaining compatibility, since all they had to do was basically support 32-bit (x86) and 64-bit (x64) on Intel while Intel did most of the hardware development. OTOH Apple had to migrate from 68K to PPC to Intel to Apple Silicon with varying degrees of control over all of them. Not surprisingly they had their greatest success when they got control over the whole widget. Apple will have some difficult and probably arbitrary decisions to make regarding the M1/M2 chips, but in the past the cleavage was mostly automatic. Seven (or six) years is a good run for the vast majority of users, and they can squeeze a few more years out of that if they prefer.