MY summer power is 17 fucking cents a kwatt! but even at 17 cents my rigs earn money.
lets say 50 kwatts a day for 200mh that is 85 cents x 30 = 255 usd for power!
but right now 200 mh is earning close to 780 a month so I net over 500 usd a month.
So if the difficulty doubles and the price drops 40%, you will make a loss. The farms must have cheap electricity.
EXP is right behind ETH in profitability...
Then SHIFT is really close.. and SOIL..
Then comes FTC.
So, there are many coins to fall back to.
YES, if ALL coins went to POS... AND electricity went up 500%+ .. yes, mining would probably not be profitable.
But neither would living in a house.. or be in a society using electricity...
Conlusion: Not very likely.