Is there any reason to think that the birth rate collapse is a long-term phenomenon (e.g. one thousand years)? There will presumably still be some subcultures t

Is there any reason to think that the birth rate collapse is a long-term phenomenon (e.g. one thousand years)? There will presumably still be some subcultures that will have high birth rates, and I imagine they will make up an increasingly large proportion of the population as time goes on. There's a lot of noise about the population decline for 2100, but I wonder about 2200 and beyond.