It is highly likely that such a proposal will be met with great opposition from the Bitcoin mining community, as this would effectively shave off important revenue growth from the big mining firms that have been recently listed on the big stock exchanges. Additionally, the proof-of-stake consensus is not as secure as the proof-of-work one, and miners are open to using green energy sources.
https://www.notebookcheck.net/Ripple-co-founder-proposes-migration-from-proof-of-work-to-proof-of-stake-consensus-for-Bitcoin.584238.0.html