WoW Arena is dead/dying. It has tons of barriers of entry, it takes ages to find a game, and it got optimized to oblivion, where you need macros/settings/builds/addons/was. But most importantly: WoW PvP has zero community, and it feels like a sales market, where people treat eachother like NPCs, and only see rating/ilvl.
Now how to redesign wow pvp fundamentally?
Make world pvp great again. Pvp in every mmo should be all about the community, not just the gameplay alone. Arena is not Ranked Overwatch. For gameplay alone, it will never succeed. Arena as a game mode makes no sense, the way it is designed currently for any game calling itself MMO. They need to eliminate sharding, and introduce open world Epic BGs, PVP zones, or open duelling areas, where people see eachother, and compete for things. PvP Rating/Elo Score is viewed as good in the community, because it removes the ego from bad players, but you know what: Rating is one of the biggest reasons, why this game doesn’t have a real community. People only see eachother as numbers, and there is no myth surrounding someone’s skill. It’s all already determined before you even interact with someone, and there are no rumours, or discussions about who plays better, because we have so many tools to measure someone in wow. This whole esports rating approach should not be in any mmo, because it ruins the social fun part of pvp, where your rating is determined by hearsay, and people try to figure out, who is better, by duelling. You should introduce server-specific tournaments for example, and give people rewards for winning x amount of tournaments in a season, or for winning some sort of world pvp war in a zone in a server. The possibilities are endless to shift rewards away from Arena Rating to community pvp events.
Soloqueue also won’t fix something for you, that is flawed at its core: A MMO, that tries to be an esport, where people just play for gameplay. Good luck with that in your 20 years old tab target game.