Several groups I know that have been running coil for months have quit, and far fewer people are doing FATEs any more if you still have characters/classes to level. Still, there are enough people playing to be able to do things if you play during the server's prime time.
The DF wait time picture was taken during Aegis prime time, so population was not the problem here. The point of the photo is to illustrate a major flaw in the in the design of the game, which is that far more tanks are required to run instances than exist. Waiting 110 minutes to join a dungeon for a subscription game, even as a DPS, and even during population lulls, is horrible.