Polkadot offers better scalability than the ethereum blockchain. It offers relay chain, cross-blockchain features, forkless network, decentralized governance and all these are not available in the ethereum network. Actually, Polkadot offers all the solutions to those problems that the ethereum network can not. So many projects are using the Polkadot network. Do you think Polkadot is really Ethreum killer?
It's not possible for Polkadot to get the Ethereum place. Ethereum is needed on for the transaction of tokens. I have one question for you, is this Polkadot will be a gas for the transaction of tokens from your wallet. From my experience, it won't replaced by Polkadot.