After reading the class rep meeting, I saw a line about boss not having CPs while players have tons of it. I think making boss having CPs might be a good way to enhance PVE difficulty. Dev will choose the CP for the instance so it will be the same for every encounters in this instance. They can hide it behind a difficulty selection system and the higher difficulty make the boss drop a golden jewelry of the dungeon drop table. Make the difficulty hard enough that players will need to reconsider CP distributions and even gear before attempting to beat a given dungeon on his hardest difficulty. So small PVE group can enjoy good difficulty and diversity while playing. You can add a death counter and score with leaderboard so players can be proud mastering a given dungeon.
Other suggestion in regard of what I said before : You can start to implement special elemental resistance set that doesn't lower too much dps stats and be used by dps in those new difficulty. Or a new consummable/build enhancements so player will spend time preparing for the content before running it and swaping to another one
Other benefits : healer will be needed again, especially with shield nerf