Miners optimise for USD$/kWh, not for coins/hash. The latter is entirely virtual and largely unrelated to the network power consumption.
which means the marginal energy cost of the coins approaches infinity
You seem to ignore that Miners, too, have to pay for their energy.
So, in your model, either the market price of the coins must also approach infinity, or the miners will just stop mining.
Miners optimise for USD$/kWh, not for coins/hash. The latter is entirely virtual and largely unrelated to the network power consumption.
which means the marginal energy cost of the coins approaches infinity
You seem to ignore that Miners, too, have to pay for their energy.
So, in your model, either the market price of the coins must also approach infinity, or the miners will just stop mining.