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?
Polkadot looks like a really good project. Time is going to tell, when developers starts making use of it they will decide for themselves which network is best for them, and they will start switching to that platform. Although we are yet to know how good the ETH 2.0 is going to be, but we already know that Polkadot has some good features that might be giving it some edge in the fight with Ethereum.
There are a lot of "Ethereum Killers", the future hasn't been decided. I have a couple killers in my portfolio but I still hold Ethereum for the most part: Universa $UTNP and Radix eXDR.
There are already so many projects that works better than Ethereum, but the odds is always on the side of Ethereum for being the first to do it. It’s just like the same thing we are seeing in Bitcoin, there are other coins that were created to be better than Bitcoin, but BTC is ahead for being the first.