Switching to ARM would kill off the Mac permanently for probably half the user base if not more. I would drop the Mac in a heartbeat, for instance (and I hardly use Windows at all, mostly just for some old games). The ability to run Windows (even if only in something like VMWare) at full or close to full speed along with even more important, the ability to more easily port Windows software is what made/makes the modern Intel Mac so versatile and changed the Mac from a glorified TOY (outside a few Pro Apps, many of which Apple made sure no longer exist since they seem to think Pros don't matter) into an actual competitive computer.
Really, even if you never touch Windows itself, the ease of PORTING software that made the switch to Intel not just a good idea, but a GREAT one given the market size of the Mac. Before 2006, you could run a few commercial packages and some limited ported games by Aspyr. Not long after 2006, the amount of commercial software ported to the Mac (including Steam and a LOT of games by other companies) went through the roof because it's so much simpler to port software for the same processor and easier still for things like games that are both Intel and OpenGL (e.g. Half Life series).
Move Macs away from Intel and you are going to lose over half your market (I mean developers) overnight and it won't likely come back because there is no ARM market of commercial software to port FROM. You put all the onus back on the developers to port TO and that's all the difference. You're right back to 2005 with a limited software base and users that need/want Windows compatibility will jump ship overnight. Boot Camp will be 'NO CAMP' and macOS will start to look like Linux's lesser known cousin that we might as well call DUMBIX because that's what the idea is, dumb. Do we really want to have to run an emulator (again) to use existing software? It was worth it before because it meant a lot of new software would be ported from Windows. NO ONE wants to port to ARM on top of porting from Windows just so Apple can make a few extra bucks in house or make their notebooks even thinner.
I'm sure some Mac users that do little more than email, Facebook, browsing and Twitter won't know or care what the difference is as they would be pretty much unaffected either way and I'm sure more than a couple of Mac users would love to share NOTHING with Windows (including the common CPU and maybe even the bus standards and even printer standards like the "good old days" when the Mac OS sucked to high hell but Mac users acted like it was awesome compared to DOS (hard to say there, but I had an Amiga so both sucked to me). But 'normal' people that aren't obsessed with Apple have absolutely no reason to like the idea of moving to ARM what-so-ever. What's good about it? What's even SLIGHTLY good about it? Possible slightly better battery life on notebooks? That's about it. Honestly, I have NO CLUE why so many people continually bring up the idea and worse yet seem to LIKE the idea. WTF are you people thinking? You want the Mac to die off permanently? That's EXACTLY what would happen. They would be FORCED to merge iOS and macOS because the only software that would be written for ARM would be for iPhones and iPads.