“Casper” is still under development by the Ethereum Foundation. (February 2018)

It is expected to be more efficient and require less mining subsidy.

Through the process, the main protocol will be switched from Proof of Work to a new consensus algorithm.

Details of the new protocol hasn’t been published, but the Ethereum Foundation confirms the following 2 features.

1. New issuance of Ether under Casper is expected to be much less.
2. It will be a decentralized smart contract that will not give preferential treatment to any particular group of people.