Won't the law of supply and demand ensure that mining remains profitable (if just barely)? This is because, if difficulty rises disproportionately to price, so that mining becomes unprofitable for some players, then those players will stop mining, causing difficulty to fall to the point where it is profitable again.
Don't forget miners with free electricity. I fear no invisible hand can prevent them from mining when their employer (or parents/etc.) pays for them.
Also, my power is significantly more expensive than in the US, so I'm out first. Again, no invisible hand to help me.
That my friend, is the invisible hand. Because it is not profitable for you, you will drop out of the market...