It would be cool if there were world events spawning in different zones called "Unstable Vortex". Players could form parties and click on the vortex to get teleported to an instanced dungeon like place. It would resemble an open world but it wouldn't be truly open world. There would be hordes of strong monsters to kill. Once all are killed, a chest with loot would spawn.
These events would be mark on the world map when they are active. Each player could do like 3 - 5 every 24hours.
I think it would be a great optional daily activity. Rewarding a lot of exp, some gold, and some cool items which would help with starting doing the end-game content.