Taking action is something you'll do once reasonable options have run out. My knowledge is of civil law in a few European countries, one of them specifically, and a judge in jurisdictions where I'm active as a legal professional will not even look at a case like this since there is no definitive proof that he stopped paying. He's working on restoring from what is claimed to be a hack and therefrom resulting loss of "coins". Although he's missed a set of deadlines, he isn't MIA so to say, he keeps updating the customers and up until now there has been regular progress. Not as much as we'd like but foul play isn't a certainty. I won't say I'm the least bit happy with how things are progressing, I'd rather have the payment yesterday than tomorrow, but at this point, he seems to be making some sort of progress. So unless there is proof he's moving all of the mining results through a mixer for example (which would lead to a possible conclusion he might be hiding the benefits from mining) or he shut down a known location he's residing (office/home) he has to be considered working on a solution from a legal point of view.

Then again, I'm still skeptical, but haven't ruled out the option we'll be seeing a payout somewhere this month. What I don't like is responses that claim it -IS- a ponzi and that everyone who hasn't lost hope is a nitwit or moron. Since that's an unjustified judgment on the person instead of on the patience someone is willing to have in a situation. Chances are slim that a scammer comes out and confirms it's a scam, on the other hand, as long as he's seemingly actively working on the website and there is progress within a reasonable timeframe I won't leave the point of view that we might be getting good news soon.
To make a comparison, I'm still getting a payout from PBMining every Sunday. Why on earth would they payout 2.4 BTC weekly (https://blockchain.info/tx-index/99501f9f9adbde1532314511ee9acd23df77477a8129bd9bb2321e068478a19e) if they could just as easily stop with that! I haven't looked into detail into everything that happened since they "lowered" payouts but I am having a hard time calling that a fullblown scam