If you are willing to do that, then make them certified ledger maintainers and throw out the entire mining overhead and make them use a good old SQL database. Sprinkle as much cryptography on top of that as you want to feel happy about unforgeability and such. The only reason to have a mining process is to allow anonymity, when you give up on that, mining becomes pointless. Also Bitcoin has not been decentralized for a long time, the idea that every Bitcoin user gets a vote in the consensus process went out the window a decade ago.