Why on earth does the mining have to use more power than a medium size country as the price rises?
Because the miners get paid with block rewards in bitcoin. As the price of bitcoin rises so does the block reward.
And as long the mining gear produces more rewards than the power to run it costs, it will stay online. And at, say $500K per coin and 12.5BTC/block that would be like $900M rewards/day or ~$330B/year. A large amount of that would be going into paying the electricity bills.
This is actually a really interesting point. I wonder then if the adoption curve is retarded by the block reward. I guess then any order of magnitude moves (such as i speculated) are some 10-20 years off.