I've been worried about this for awhile since exchange revenues went down. Needless to say, I've left nothing of value on Bittrex and a couple of others. We just got lucky with Mintpal and their recent hacking.
Everyone would be well advised to move assets to safety.
To be quite blunt, there's a damn good reason for doing so even if the endgame isn't a grab and run. By doing so, you send a signal - the only signal that matters; declining volume and lower trading revenue - to Bittex managers that it's high time they cleaned up their act and got choosy about new listings.
I can't join you right now, as Bittrex is the only major exchange that lists Quebecoin which I'm trying to pick up right now, but I can say this flatly:
As the head dev of NFD, I have now lost all interest in getting NFD listed on Bittrex. In fact, a teeny part of me would prefer that they don't list NFD.
Their listing policy has gotten so bad, I'm a little bit worried about NFD being tarred by the same brush!
Feel free to quote me on this.