i dont think ethereum will become zero value in short or mid term unless vitalik doesnt quit from the project. because ethereum blockchain is still being used by so many projects. and it is really useful.
But I don't think that the person behind this project will just give up easily, it for sure he will do something good and to prove that Ethereum still worthy of our investment. It is in his hands and we can do nothing if ever he'll quit.
We know how Ethereum creates its reputation and Vitalik Buterin isn't a person who easily loses his appetite.