Is Proof of Work is going to lose popularity compared to Proof of Stake? Ethereum is going to PoS. 
Is there going to be a lot of hash (computational) power idle because of shifting to PoS?
Where that power be used then? Will it address such decentralized computing projects as Golem, Storj, Sia, etc?
By volume or marketcap Bitcoin and Ethereum is the first and second coin. Bitcoin has maximum supply 21 millions and Bitcoin is support POW. Now Ethereum is interested on POS for future token supply. Without buying any Ethereum you don't know the real value of Ethereum, now you will get rewards for it.Is there going to be a lot of hash (computational) power idle because of shifting to PoS?
Where that power be used then? Will it address such decentralized computing projects as Golem, Storj, Sia, etc?