I don't think it will kill Ethereum, it just becomes another possibility to run transactions on.
It will become a competitor but it will not kill Ethereum.
It will be another alternative chain for ethereum and that's the only thing that can be achieved by DOT. It's quite impossible for DOT to replace ethereum as the best smartcontract platform.
People are putting ethereum as the best choice for the tokenization purpose and defi development.
They will not try to move into the another platform.
Some projects that decided to build their dapps on DOT just wanna to get the ride for the hype.