It does'nt seem to me that it has been discussed yet, however this function has been available for a few days at a modest price on Sequencing, which by exploiting raw data allows you to elaborate a map dedicated to the similarity of autosomal with that of ancient samples (the greater the circle / point the higher the proximity: clicking on them displays the details of the sample).

It is somewhat competitive to some MTA tools and perhaps it can be adopted as a comparison tool