not just north america, dota is dying in europe too.
SEA, china, south america and russia are the big bastions of dota players today. NA was always sub par and small, and western europe is dying off rapidly too.
for now, western europe is kept relevant by the huge amount of veteran pro players that have been around for over a decade and still compete at the top level, no other region except china has such a strong and experienced talent pool, but there's barely any young talent coming up to carry on the torch, so as the old guard retires, western relevance will slowly fade away from the competitive scene.
and yes, you are right, this drama will barely affect the wider dota community at large, but it will hasten the decline of the western pro scene and all the producers and content creators who have made careers off attaching themselves to that scene.
you are wrong about that "the english speaking audience is waning" part though. even if NA and EUW were completely removed from the dota scene, all the international events would still be done in english language because that's the only practical way to do it. you definitely won't be getting peruvians and russians to learn mandarin, nor chinese and malaysians to learn spanish.