The developers of Ethereum presented the technical characteristics of the first phase of the upcoming update, Friendly Finality Gadget Casper (FFG Casper), which will allow the network to switch to the hybrid mechanism of the consensus Proof-of-Work (PoW) / Proof-of-Stake (PoS). This is reported by Trustnodes.
In particular, the documentation specifies such an important parameter as the award to the miners for the block using the Proof-of-Work algorithm: after the new rules come into force, it will be reduced by 80% - from 3 ETH to 0.6 ETH.
In this proposed spec for stage 1 Casper, Ethereum will transition from pure proof of work to hybrid PoW/PoS. In this scheme, all of the proof of work mechanics will continue to exist albeit with a reduced block reward (0.6 ETH), but additional proof of stake mechanisms will be added. In particular, the fork choice rule (ie. the way that a client determines which chain is ‘the canonical chain’) will be modified to take these mechanics into account.
It is also noted that the rules of fork's selection (the way by which the client defines the "canonical chain"), will be modified.
The published documentation does not specify a reward for PoS-miners. In theory, one might assume that the remaining 2,4 ETH will be redistributed to their advantage, but given the significantly reduced cost of this method, it can not be ruled out that the reward will be even lower.