When enough of the SGA items have been "digested" by the game through failed tier attempts or deleted accounts, they may do a limited event. No doubt with huge impossible mobs and the need to spend thousands to have a chance ;)
Wow they took my advice, I suggested this two years ago :D I'm sure I'm not the only one since lots of games have a similar area, but glad to see it getting done.
Most of the people who got fed up have quit, the people still playing know what the score is and have accepted it. That said there are still plenty of whine threads around if you look for them :D
A couple years ago one of the CND shops had a great skull museum set up, far as I could tell it had every skull in game. But I have no idea if it still exists.
Found a screenshot