I don't think so. I mean, as far as I'm concerned, it's all effectively a pyramid/ponzi scheme (albeit legal and out in the open); but as you referenced their BTC holdings, there's an awful lot of built-in cushion before things really get ugly.
In short, shareholders aren't really losing anything yet, unless they choose to sell. I think the first sign of the beginning of the end will be the board choosing to exercise their option not to pay STRD dividends.