If bitcoin really became the backbone of the world's financial system, as every bitcoiner dreams of
It is not my dream because I am living with reality.
Governments and central banks will use blockchain technology to build up their Central Bank Digital Currencies CBDCs but they will not directly use Bitcoin blockchain for it because they have no control on Bitcoin blockchain.
it will be impossible for anyone to have a transaction confirmed on the main chain. The fee price will be so high that only corporations, financial institutions and governments will have the cash flow to do it. Second layer solutions demand a main chain transaction, so it won't help. Even early adopters will be forced to move to second layer solutions.
Has Bitcoin protocol been upgraded many times since 2009?
Think of its past upgrades technically, you will easily see how Bitcoin protocol will continue to be developed and upgraded in future to satisfy with new challenges, new demands and bigger opportunities.