The Luna Temple map is currently a deserted relic with no actual purpose in the game. It's empty most of the times while having some of the coolest and unique monsters in the game. The map serves little to no purpose within the game, which is a shame because there is alot of potential with some small tweaks.
My suggestion is to revamp Luna Temple into a clan based dungeon(non instance) on a 12 hour timer, with best in slot items dropping from the bosses and a bunch of other rewards for participants. Here is how I imagine what this would look like:
Map
Bosses (Objectives)
Normal monsters
New Items
Rewards and Drops
This mode would bring alot of content relative to the amount of work it would take to implement(I assume). Having this gamemode solves alot of current issues with endgame:
No clan based conent
Empty zones (Temple in this case)
Lack of chase items
Making exalted gear very useful for this mode (PvM + PvP bonuses)
This suggestion is a work in progress and has possiblities for alot more content, please leave your own suggestions in the comments. I really think changes like this is what can make the game lasting.