Earlier quoted context omitted.
> prunes out as many languages as possible Would you feel the same way if that includes all languages you know, including all versions of English?
Yes, I’d be happy to learn a new language if it was the step to one unified language. Of course there is no way to back that up since it will never happen but I at least assume I’d do it if that was the case.
It's not just about becoming bilingual, a population becoming bilingual in a "prestige language" is the first stage of language death (though of course it doesn't /always/ lead to language death).