Ultimately it's just a case of facing reality. Even if M1 itself won't be enough, it's pretty clear where things are headed.
Apple itself is going all in on this, they have a vested interest to make this good and move their whole ecosystem to effectively single unified architecture and Apple is big enough and influent enough to actually move the market in that direction. It's not just some yet another shitty fringe ARM laptop where they stick an actual tablet CPU/GPU and build a laptop around it as some afternoon class project for curious.
Here you have whole Apple moving all of its product stack there and for Blizzard and others it will be a simple reality of either you comply or you lose that part of the market, it's not insignificant and whatever work will be done porting WoW there - they will need to do anyway eventually if they want any Blizzard games to be in future Apple machines at all.
And as said before, it's really not only Apple there - it's ARM, that's a LOT more than just Apple. The incentive is there like never before, because before it was just what - make WoW run on phones as some kind of meme? Well now it's a whole different story - make WoW run on all Apple hardware AND ARM-based phones/tablets, even if that would require extra leap with different render API and such.
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As a side note, I don't get that guy directly above this quote. Who cares if M1 can run WoW at 4k - WoW is a game that's meant to run on a toaster, that's why it has so much reach. M1 clearly has all the CPU power it needs and if its GPU is not up to snuff (which remains to be seen), then for now it will just run WoW 1080p until 2nd generation of Apple Silicon comes, which will be pretty soon - you can bet. Apple's own ARM configuration can run Fortnite at 60FPS on iPad Pro, heck it can even run 120FPS on latest model with issues, but it can get there. And M1 is a lot beefier than that.
You think it would not be able to run WoW at 60FPS on low settings native resolution? Funny...
Speaking of which: https://www.tomshardware.com/news/ap...cs-performance
Seems like M1 has GPU juice on par with 1050Ti and even greater - I can assure you - that is more than enough to run WoW at 60FPS. My MacBook Pro runs WoW natively on GPU a bit worse than that - RX560.