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?
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?
1.- I don't think PoW will lose popularity, but in the long term, people will choose PoS because it is more friendly with the environment.
2.- In theory hash power should go down, because since PoS doesn't need the robust miners we use nowadays, then that's why the hash should go down.
3.- Miners who was used for ETH could easily be used to mine another coin.