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?
Indeed Polkadot is one promising interoperability project. Like ethereum, it intends to add more superior Blockchain projects, perhaps. considering that one of the core ethereum teams is supporting the Polkadot project. However, it can't be denied that ethereum plays an important role for many Blockchain projects that use Ethereum smart contracts, obviously there will be tough competition between polkaDot and Ethereum in progress and development