My wäwa wrote that the last Ngandi lady who knew everything recently passed away. He makes some really good comments about language death and the term “extinct”.
I think this is one area where being too picky about the definition of language competence is very unhelpful in practical terms. Sure, from the point of view of studies in the theory of language death it’s useful to be able to quantify various stages in the shift of a population from one language to another, but in terms of revitalisation and community involvement Wäwa shows clearly that it isn’t helpful, and that languages like Ngandi continue to serve a very important function, even if it’s not the same function that they used to serve before.