Could decentralised proof of time in BCHSV solve for high PoW power consumption?
Mining is the timestamp in Bitcoin, it allows for a decentralized system to achieve synchronized ordering of transactions with high probability. If a system for doing decentralized time sync existed there would be no need for mining blocks at all, you'd simply timestamp transactions as they arrived and call it a day. 

No system for this exists, hence we use Proof of Work to achieve an approximation.