Redo all the dungeons for a hard mode updated to the latest master level and put in rewards that matter to players in OBB. Scaling the dungeon difficulty to what current ML40 are capable of is enough, the mechanics and everything else can be the same. The rewards could be something similar to HHBs content; alternatively, the materials we may obtain in OBBs should be used to craft the latest pve-gear or pve set with slightly different stats and bonuses, of course as a viable alternative for best pve gear.
I believe by doing this would make all the LOTS dungeon content interesting to players and revisited.