Unless people are actively trading bitcoin enough where the transaction cost because an issue, there's little reason to trade in their tulip bulbs for iris bulbs. A bet on a cryptocurrency is a bet that people will think it's worth more money, not an investment in the underlying technology.
Does it though? There are so many things to consider when talking about the "energy usage" of traditional money. All the vans moving money around, manufacturing, items to support PoS systems, sorting, protecting the money and so on.
Yes, so many things that BTC will never do. It's vastly less efficient and offers nothing like the range of services and products of the existing finance system.
Cardano is the top cryptocurrency currently on PoS, and while I agree that the next cycle will be the ETH cycle, I think the one after that could be the ADA cycle.
I am especially interested in assessment about CO2 emissions from credible sources (please, no VCs with zero training in physical sciences posting thought leadership pieces, I beg you).
What the long term inflation rate will be then is really set by the demand for transactions and how much congestion there will be on their network, driving up transaction prices and fees burned (or not).