the freedom of somewhere which doesn't expect cabeceo/mirada, or other códigos, and the issues of being invited to dance
so essentially a place where verbal invitations from either role are de rigueur? I can see how it appeals to them. If one
already knows (and dances, I guess) with enough people, then no matter what kind of event it is, you achieve the same effect.
Alt and nuevo sometimes seem to combine, so sometimes seen as the same thing. At others there's a fusion. But you're right that these degenerate into some uncertain fusion mix.
Very few people now still conceive of tango nuevo as the system that is the brainchild of the Naveira/Salas gang — it's become a catch-all term for
dancing any kind of tango to alt/nuevo music.
Then what about the context of music, as opposed to the context of dance/movement?
Even as a DJ, the way I categorise things isn't universal at all — I generally tend to call songs that aren't meant to be in a tango context (like AWOLNATION's Sail, Sineterra's Ariele e Calibano)
alt, while songs that are at least tango-related but not within the purview of traditional or modern tango orquestas/groups I consider
nuevo, like Craig Einhorn's Milonguea del Ayer or Alper Akgul's Milonga for Moonlight.
Even so, there's a lot of overlap. I love Amores Tangos' Toda Milonga, but I'd call it nuevo-ish. Milonga para as missões is great fun, but I'd still call it nuevo too. Then you have stuff like Hyperion Ensemble's Ludwig van Milonga. Is it tango moderno? Is it nuevo?
Then there's the milongas camperas like No soy aquí, ni soy de allá or the milonga uruguaya, El Violin de Becho, by Zitarrosa. Maybe "nuevo" as a term for music has become too broad, but that broadness gives us DJs much more flexibility in creating tandas.