Looks like Ymgarl Genestealers will be added in the Leviathan Rising dataslate that has a picture of one on the cover. So now that you already spent $50 on a book you will have to spend an additional $15 to use your old models. Oh wait, they say this is the first of a trilogy, assuming they all cost $15 means you may need to spend $95 on books to play your army. That's on top of the $80 basic rule book and escalation and stronghold assault books you might want to play with. Never mind the cost of models and paint, maybe one of the reasons their stock plummeted?
If they wrote one comprehensive rule book (like warmachine maybe?) and didn't charge ass loads of money for it, maybe they would attract more new players. I just hope that if a new edition is already in the works, they add some form of skirmish rules to play on a much smaller scale.