I think for whites it might actually be a distilling effect honestly. Tons of whites with dead end genetics/culture are not breeding. The only whites breeding at higher than replacement rate tend to be right wing blue collar workers and probably more real engineers and scientists than you imagine. Whites will lose a large number of individuals over a few generations but the ones moving forward will be much more in tune with their tribe and hopefully will turn away from the path of decay and preserve a smaller albeit more zealous core group.