The good news is that you are stressing out over a short term issue that does not need to be solved .... once the reward drops to a level that is not economic for all but the most efficient operations.
I don't feel stressed at all. Thank you. Let POW be with us for as long as we see fit.
I don't understand how the convergence towards efficient operations solves anything. It may be efficient in terms of profit margin, but can still be wasteful. After all, bitcoin users will pay for each consumed kWh in terms of transaction fees.