I think the real test will be whether or not the SEC files suit. They not only have more information available to them than the CA suits, but they know the likelihood of prevailing in such a suit based on the evidence they have collected.
The Wells notice is not a good sign, but it's also not a guarantee that the SEC will proceed. If they do, I suspect a settlement will be quickly forthcoming, but unfortunately, a CA suit is likely to follow, particularly given the likely further steep decline in the stock price. Following behind the SEC in a lawsuit is a pretty strong position, and of course, an SEC suit is likely to hit the PPS hard which will bring more potential claims in a class action.
Should the SEC decline to file suit, I would think that any CA suits will quickly vanish.