Miners not getting paid enough rewards in transaction fees so either the price of bitcoin must double constantly
That doesn't really help, since the potential profits of a 51% attack also scale linearly with the value of bitcoin. For proper security, the daily miner revenue must be a minimum fraction of the total market cap.
The *only* way to preserve security in the face of halving block rewards is to similarly keep doubling the feerate.
That's because it's practically guaranteed to never happen. Nobody who owns Bitcoin will agree to let it become a money printer.
Immutability and a 21M hardcap are core essentials of Bitcoin. Only shitcoins make changes that violate their principles.