It would really be exciting to see a hypothetical tournament with some of the most famous defunct national teams: Czechoslovakia, Soviet Union, East Germany, Yugoslavia, Saarland, South Yemen etc, obviously only with the aim to commemorate the history of the various countries and national teams, and not to awake nationalistic feelings.
Yep, I'd hope the world is mature enough to see such matches as a recognition of history and chance to learn from it (in the more controversial scenarios) rather than a ball of offence to be taken or given, I personally don't have such a situation I can really relate to so I'm looking at it purely objectively.
For example, the country that the famed Hungary team of the early 1950's represented I'd consider a semi-detatched entity
to the current one, and while that was a brutal dictatorship, it doesn't mean the country as a whole and its people at the time shared those views (as history shows), and it would be the latter two factors (especially the second one) that you'd hope any modern eligible Hungarians would want to honour by playing under that flag
if the opportunity came up (although I suspect being the zombified successors to the Magical Magyars would be plenty of incentive in that scenario)
Meanwhile, I found evidence of the East Germany v West Germany modern match that I mentioned in the old post I linked to, unfortunately it was just a recreation of their 1990 match with teams of legends
, but it's something at least... maybe they'll keep doing these reunion matches every couple of decades until the players look more like this