Intel generally supports a lot more modern instructions, Apple has taken ARM quite a ways but it is still no competition for x86 high-end CPUs. Apple may change that, but the other problem is the lack of software support for things people typically do on x86. X86 has carried support for a line of CPUs for decades, so there is surely going to be bloat. ARM typically has problems with some of the tasks in modern desktop environments, like for example it sucks at video encoding compared to x86.
ARM does well on servers but going to be a long time for them to do anything to the desktop market. Apple has drastically increased its desktop market share but it is still only 15-18%.
According to a fairly recent IDC report, desktop and fixed workstations are projected to have a 21.3% market share where as notebook and mobile workstations will gain 45.9%. We could also add "edge computing" into the mix. It's projected to become market of $18 billion by 2022 and a point of major focus of computing as the industry moves forward.
I was referring to Apple's share of the desktop market