I agree with you on Tor and/or i2p. I don't know if you can be as categorical as "It'll never go down", but at least it will be significantly harder to get it down. And it can be anonymous, which is important of course for the people offering the service, but also to protect the users of the service…

I don't know if such a website can survive to the scientific publishers' lobby, especially when its builder is publicly known.

Edit: it seems this exists, as another comment point out on this discussion page.