Half of hedge funds are going to disappear in the next few years. That's something many of us have expected for at least a year.
As for their money leaving the market, I think the selling for redemptions is basically taken care of.
Remember, just because a hedge fund folds and they return the money to the investors doesn't mean that money stays out of the market. It will find its way back, but the leverage the hedge fund employed will likely be replaced by a non-levered position.