New cryptocurrencies are using much less resources due to proof of stake model, Etherium 2.0 being one example. It’s possible that some day in the future bitcoin may he converted to proof of stake also.
That's not going to happen. The core reason Bitcoin is the hardest money that's ever existed is because of proof of work. Part of why Bitcoin has monetary value is due to the energy used to produce Bitcoin and to secure the blockchain.
Eth 2.0 is unproven so far; it certainly wouldn't be trusted as a global reserve asset in its current form.
Pure proof of stake is fantasy. That's not "Bitcoin" and it never will be.
My personal hope would be that mixed proof of work and stake with on-chain governance, like Decred (their devs have built much of the Lightning Network tooling, performed the first cross-chain atomic swap, etc.) - could be adopted; but, realistically, I think that's also a fantasy.