Ironically, I could have told them that would happen. I've seen it in dozens of PBM and PBEM games.
Step 1:
Open speed world/game/universe.
Step 2:
Ordinary games lose players as they can't keep up with the speed game time commitment without dropping in regular speed games.
Step 3:
Watch players who jumped to speed game get burned out faster & frustrated easier, so they quit altogether. Admitedly they paid more $ for the speed game, but they concentrated their spending on one world/game/universe, so if they tank there, they have no other good positions to retrench to and take a breather while still playing.
I was posting in the GD forums, and sending in the occassional ticket asking for a slow-down world to help keep coaches who are burning out. I don't know anything about the past of HD, but you're saying that:
1. Tark opens (I knew when this happened - people let me know WiS had opened up different spped games, which I was talkign about then)
2. A bunch of people add Tark, so they can get in on the ground floor AND speed ahead to their dream school.
3. After realizing time demands, people start dropping other worlds.
4. Now people are moving up in Tark, and no one is coming in to replace them.
regarding #4: new players generally don't want a high-speed game. It gives them more chance of making errors, less time to learn.