Guild Missions are fun, they always need to get expanded, but how about Missions for groups (regardless of guild)?
I know we have that, it is called instances, but it could be an extra element added daily to dungeons, that could change a certain mechanics or opening a bonus event (optional for those that just want to clear the dungeon).
On top of that, they could add “gambits” to normal dungeon, increasing it’s rewards.
Another thing I’d love to see would be those FFVIII style missions. Remember right in the start when GUARDEN sends you to a town to take over some TV or something like that? We all started in a boat rushing to it, with events and bosses.
It could be “adapted” to an open world version: It would be long chains of events that we know where it starts and most importantly when.
Now, how to prevent those events to be our current zergfest, I have no idea.