Ethereum killer? It seems an exaggeration to call it that way, although it cannot be denied that Polkadot has the potential to be a tough competitor to ethereum compared to other platforms, even platforms like stellar and neo are not able to match it.
Yes, it is a bit excessive to call him an ethereum killer and it doesn't seem that easy for sure,
after all ethereum is still the top coin and ethereum will certainly continue to grow,
despite all that I think polka-dots should be applauded because they have come this far