No one knows for sure if Blizzard will continue to support the Mac platform. They are under new ownership. The next 2 years will tell what direction they have for Blizzard as a whole.
We do know that they have essentially gutted the Mac development team. We do know that the M1 client was due to their investing time in a preliminary ARM client of Windows, not so much because they wanted to support the new Mac platform.
The GPU situation on the Mac is still in question. While the CPU side of things runs circles around current Windows architecture, the GPU side of things is still lagging behind in terms of graphics intensive applications such as gaming. Apple has yet to show any real jump in GPU performance. The Mac Pro is their last chance to show whether they can compete with AMD et al.
We know that Blizzard hasn’t offered Mac compatible versions of most of their recent offerings. We know that the next expansion won’t likely hit until 2023 or later. We know that support for WoW has been essentially abysmal during Shadowlands. The newer architecture has it’s own issues just like the older architecture has it’s issues.
So, if you are looking to replace your current rig just so that WoW plays better, that to me would be an unwise investment. If you are replacing it for other reasons and you would “like” to be able to play WoW on it, that’s a different story.
Just in the last year and a half we have seen the M1, M1 Max, and M1 Ultra… the M2 is destined to replace them in short order. Apple is making a lot of changes. Blizzard will be making a lot of changes. Whether that includes the Mac platform going forward, no one here knows.
The key is, if you are concerned about Mac support going forward, then don’t buy a Mac to play games on. The one absolute is that Windows will be supported. If you don’t mind playing WoW on a Mac in a depreciated state, meaning, with limited support due to whatever reason, then go ahead and get a new Mac for playing WoW. Just don’t assume the flagship Mac coming from Apple will be better than it’s PC counterpart when it comes to support and playability.
You need a Mac development team for that. And they gutted their team.