yes but their fantasy barbarians will be Darkoath and their leader will have boobplates and a northern accent
Also worth considering that if we can now use multiple command abilities, would cheaper but more plentiful heroes might be more useful than big point sink heroes?
I hope they do it, and yes that would make perfect sense for the giants, skin wolves mammoths, warshrines and all of that other never quite was part of a chaos gods chosen portfolio of stuff.
I see them almost like they were in the old world, not worshipers of chaos as such in the same sense as bloodbound or warriors of chaos but people who live under its skies - the same as the humans who fought along side the undead in the Shyish against the nurgle incursions.
I'm biased of course as it's pretty much the army I run with my slaves to darkness, marauders, mammoths, curs'd ettin warshrine, and horsemen. Maybe they will become what models are left from the slaves to darkness if they don't become part of the everchosen, or maybe thats the separation - armoured slaves become everchosen, and nekkid slaves become darkoath. who knows!