I previously considered an option that the network would be secured by competition for control (even with potential monetary losses), but was confronted with a notion that it was not economical. So I kept thinking.
There are many other ways to secure the network , like not exclusively relying on the PoW algo, but adding others which have different security considerations , benefits and weaknesses to PoW. This would make bitcoin more robust and secure. Another possibility is that nothing needs to be done because BTC grows so much that valuation alone stays ahead of disinflation or the laws of economics and thermodynamics force miners to make consumable heating devices to pay for security.(solving the centralization concerns as well)
Other possibilities of securing the network include using sidechains which perform useful tasks like folding at home, or cracking codes, selling cloud storage, ect... all give subsidies with tx fees to the mainchain which provides security to them.
Other possibilities is that volume alone can provide network security - 500k a block x 1 penny per transaction = 5k usd a block in security
We don't need to throw away our core principles so quickly without trying creative solutions to solve these problems.