Of course, neither is it proven, for now, that those adna lineages are, indeed, extinct. What we do know, however, based on actual research, is that certain lineages, at least in certain areas, do indeed go extinct, some predominate, and others become minor lineages. Also, for now, the process appears to be random. (Did you bother to read the paper?) We also know, from mathematical modeling, that this should not be a surprise.
Without a much better understanding of the statistical fluctuations, the actual mutational processes involved, what role, if any, selection plays etc. etc., all these speculations of this or that superior tribe moving to x or y area, are just fairy tales, and usually fairy tales based on some jingoistic or racist agenda. This whole hobby is really getting to be a waste of time.