Aside from updates to base UI/DR trackers and obvious stuff, here are my ideas.
Remove pvp from old versions of wow and only keep pvp in retail (and sod since it’s kind of a unique experience) Add in season tournaments/micro seasons. Change LFG/add rewards to it. Mix in special arena days.
In season tournament/micro season ideas:
Like a weekly/monthly reward for playing the game. Maybe players in the top 1% of each bracket get a wow token. (Top end of each rating bracket) sounds silly but could help. Just imagine the top 2-3 Players at the top end of r1, glad, duelist, rival, challenger get a wow token. And you can only get 1 token per season to avoid people abusing the system. Idk just an idea.
Or seasonal rewards for all players, but mainly a focus for new or improving players. Like each 100cr you push after 1k you get a loot box at the end of the week with a chance for rare cosmetics, random old mount, maybe even the pvp gems/high end mats for gold farming.
LFG/RAF idea:
Add a recruit a friend type system to LFG to incentivize higher xp players to help the newbs learn or just to incentivize people to play with randoms in LFG for more than 2-3 games. Could even be as simple as any win with a team from LFG gives a loot satchel, just containing gold and mats maybe a low chance for bonus trading post tenders idk just another idea.
Special arena days:
idk if anyone plays Pokémon go but they rotate weekly battle leagues, it would be cool if like every Wednesday we got a time walking styled arena where they scale it down to lv70 tbc content and all the old tbc gear is relevant for that day. Would incentivize ppl to engage in old content and farm gear kind of like with what mage tower did. They could just rotate through all the different xpac/level caps. Maybe it would get all the pvp nostalgic seeking people back in the game, this could also be a way to incorporate some old seasonal rewards as it would be like a pseudo season of the original season. Could make it super grindy to make the system last a long time, ie on cata arena days you can get one piece of the elite set, so it would take like 8 cata arena days to build a full elite set and on a rotating schedule with other expacs it could take a year to farm the elite set. (This would probably take the most effort to implement and buy in from the community as there’s so many questions. what are the rewards, what is the tuning like, are pve items nerfed, what about old power systems, how would this affect normal cr/mmr? Is it the same rating or different?)