Just had an interesting idea that might be fun. Players could do a one of 3 or 4 quest lines that give them access to different elite specs, waypoints, or buffs. These specs and buffs would be across all classes so they would have to be pretty tame as to not cause too much conflict. But if one wanted, they could just sign up to do a different quest line to switch.
Since everything is getting pretty homogeneous as far as classes go you could have the specs be the general dps, tank, healer builds. They wouldn’t have to give access to a new weapon, but could instead give a permanent or periodic buff.
As for plot to back all of this up, they could have the players attempt to get the aid of remaining gods to assist with the dragon problem or to retake can the, elona, the frozen north, or to help with dealing with Ryntlocks story ark.