It's more than 3300. With S9's I would guess it's around 6k a coin at current difficulty. Granted you could ratchet the diff down slowly, but I think they're mining at a loss now to wave dicks. Eventually they will have to pay investors/electric bills/bribes.
Devils in the details, no?
There is going to be a difference between the efficiencies of small miners and depending on location (electricity costs), so would the average for BTC be closer to $3,300 or $6k or do we not have better information to narrow it down a bit? Of course, the more efficient miners with the lower costs, may well be o.k. with some lower prices in order to hope that some of the less efficient miners, on the higher end of the spectrum get out of bitcoin hashing services.