RE: Bitcoin Technology Must Move Forward
Quantum computers are a threat, which could be easily solved. In fact, some blockchains are at this moment quantum-resistant such as NEO. I think BTC can be also updated-forked to be resistant.
About the energy consumption, this week Charles Hoskinson (CEO of IOHK) said that Cardano blockchain can be run by energy, which can run one or two houses. So there are simple possibilities in crypto sphere. I am not sure about Bitcoin transfering to PoS, but others can do that, such as Ethereum.