WoW may not support that many cores but the OS will use what cores are available so got background tasks it will be moved to there based on CPU drivers.
The days of one core being the fastest is over, the new things are what can a CPU do per cycle tick. WoW is going to have to move to ARM when Apple moves over to that so there’s work to be done for Blizzard anyways since apple is moving away from x86 now.
But not heard anything from Blizzard on that or any other games developer as most of their games/software will have to be rewritte to support ARM code than x86 code.
But don’t worry about cores on a CPU now, what you can get now is going to be better than what you may have had in the past. Things are always improving with each new cpu that comes out.