Definitely anything to improve PVP.
1. Improved PvP system/rewards that allows PvP to be an alternative for PvE grinding. There is absolutely no incentive for more experienced players to press that PVP button when the same rewards can be gained in <1 minute from AI3. A better matching system needs to be implemented rather than a totally random process that ignores a player's score. Even being able to challenge another player via PVP Duel but an option for stakes/reward to be involved.
2. PVP ranking/score system. Adds another dimension to the game.
3. PVP tournaments/league matches handled by game server rather than a 3rd party via forum. Will most likely improve accessibility and participation.
I'm not sure if any of these are in the works. I hope they are! Either way, I'm anxiously awaiting for any of these additions.