1. Cap leveling once and for all, at a specific level, say 60, and no more leveling beyond that, ever.
2. Gear based progression based on BiS pieces instead of ilvl. New raids and BG's instead if new zones to quest in and level up. The world is already too big.
3. Zone scaling 1-60 in classic zones, 1-60 in Outland and Northrend zones, 1-60 in Cataclysm and Pandaria zones, 1-60 WoD and Legion, 1-60 BfA and 9.0, basically 1-60 everywhere, so new toons can be leveled starting in any of the expansions or classic zones.
4. Bring back class identity and hybrid builds via talent trees.
5. Quest rewards, mob drops and profession items than can be used in combat, as cosmetic items..etc
6. bring back 20 and 40 man raids.
7. Remove mythic and leave only heroic, and normal mode dungeons and raids. 2 difficulties are enough.
8. Convert LFR into solo raids that can be done with AI NPC and AI driven player alts. This way this system does not have to be fully removed and can still serve a purpose.
9. Let players just buy flying after fully completing the main story quest lines. That means the player has already fully experienced the content once, why force them to repeat the same quest 1000 times in the same zone.
10. Scale all raids to 60, the difference being gear stats.
11. Let players do solo previous expansion raid Xmog runs with AI driven alts and super powerful AI driven NPC's that can obliterate the whole raid just like a 120 player could in a level 60 raid.
12. Bring back gear sets.