WoW should have a patch dedicated to return of class halls and character customization.
There should be like a quest line that leads back to level appropriate and updated class halls, that come complete with a ton of cool class specific customizations you can earn from them. Even more, maybe they could be upgrade-able with currency from current new areas to allow for improving looks, adding amenities, etc.
They should come with a ton of cool weapon transmogs, armor sets, alternate skill appearances that you can earn for solo challenges, etc.
For example, there could be a challenge involving Chaos Bolt in some way and that allows warlocks to earn the old appearance for Chaos Bolt (green dragon head).
Even more cool maybe this patch could allow for updating of mob levels and world quest levels in areas like say Zuldazar or Drustvar, amazing visually impressive and immersive areas that are now just sitting there, empty and rotting away, unused despite being so awesome. Imagine if we could go back there and there would be PvP objectives and cool world quests to do that would reward you with actually expansion useful stuff.
I’m not developer but if this was up to me, this would be TOP priority. THIS is what this game needs, more character customization, solo challenges, class halls, and return of fan favorite areas for WQ or outdoor fun - heck that could even be on a weekly rotation to not spread everyone too thin.
Think about it Blizz!