When we finally get AI to work language of legacy websites won't be a problem.

The problem with AI translation isn't that the AI isn't working, it's that humans don't express their thoughts as clearly and consistently as they'd like to think they do. Even a human can't create a 100% accurate translation of a text without knowing exactly what the author was thinking, and language is a very poor mechanism of conveying thoughts, based on the author's expectations of what different words correspond to in other people's minds.

I do expect language to become obsolete, i.e. showing someone an illustration of something instead of describing it to them. English might be the last language in use, but its vocabulary is only going to decrease.