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.
You make an excellent point and in the long run perhaps the mining system may prove flawed.
But I must have missed where in the near term the cost of a bitcoin is anyway related its mining cost?
I'm sorry, but you are wrong.
If bitcoin price is 10x higher than mining costs then a lot of new miners will emerge ... simply because they can make some profit.