Yes, and it has already been done. https://coinmarketcap.com/currencies/bitcoinpos/ https://coinmarketcap.com/currencies/bitcoinpos/ Bitcoin is open-source so

Yes, and it has already been done. https://coinmarketcap.com/currencies/bitcoinpos/ https://coinmarketcap.com/currencies/bitcoinpos/ Bitcoin is open-source software. Anyone can fork the code and change it however they want. Just need to convince others to run a node with your code and convince the market that your new network protocol is worth something. However the history of Bitcoin hard forks has shown that they're all almost certainly doomed for failure or irrelevancy, because one of the main value propositions of the original Bitcoin is that it's resistant to change by any single authority. Want to replace the original Bitcoin using PoW with a new Bitcoin using PoS? You have to convince everyone running a Bitcoin PoW node (~50k globally) to switch over to the PoS client, including all the miners around the world (~6k globally). Why did it work for Ethereum? Because it's centralised. The community will follow the lead of whatever Vitalik and the Foundation states is the path forward for the protocol. Bitcoin has no such centralised leadership and so is resistant to top-down decision making.