How would the Proof of Stake, if implemented in time, work for Ethereum?
Would Ethereum solve their scalability issue?
Does Ethereum decentralization give it an edge over other centralized smart contract platforms?
I think this question should be asked Vitalik Buterin.

.Any project moves according to a roadmap..I hope this link you will find all the answers to your questions.
https://www.ethereum.org/learn/