For what I understood Casper will not modify the way of PoW works.
Casper is just a new PoS protocol. which should help maintain the network secure and avoid the great waste of electricity required by GPUs in order to works and maintain the network secure.
It is a good question because no one knows what will happen with this new consensus algorithm! so many people are skeptics about it. only people who has a minimum amount of ETH will receive rewards... I heard a lot of people saying that ETH will be more less decentralised with Casper...