Idk man i think it depends on what part of pvp. People play arena for the fomo stuff but i think people tend to play battlegrounds for fun. Sadly most pvp focus is on arena because blizz really tried hard to make esports happen. So some more bgs and maybe trying some new kind of pvp modes would be good for that.
But yeah pvp mogs from previous seasons should become avaible after a time. Maybe not directly the next season but it would hurt to get it an expansion or two later when it would become “legacy”
Well they could make something with vehicles. After all we got dragonflying now wich is basicly a vehicle with better movement and control. They could do stuff they once wanted to do with wotlk. Wintergrasp was first supposed to have aerial combat as well but was deemed to clunky.
Blizz loves to take ideas from other games so why not try that idea and have some sort of scuffed warthunder/world of tanks mode
Or maybe just plunderisle with out characters but limit the abilities you can use there, or downscale all players to lvl 10 or 20 or heck maybe even lvl 1 and then let all your abilities/weapons be about what you pick up during the match