As you wrote, it is not clear if DraginMint is real or scam but also with the slightly higher hashrate these will not do the job anymore.

Many mining farms are located in regions with power cost as low as 1 cent or little more; this still gives a pretty bad ROI based on your calculations.

There are no rumors yet if Bitmain is working on the next generation of Antminers. This development could improve profitability by a boost of Hashing/power consumption ratio.

The central question remains: what happens to bitcoin mining once it is no longer attractive to mining businesses. We have seen a massive increase in transaction cost, it might be that​ very soon, transaction fees are the only income stream for miners, and thus transaction cost will skyrocket once more. Ultimately this might kill Bitcoin as BCH, and other Altcoins are going to be even more attractive to the big players in the mining business.