Typical rightist demagoguery. Number of people does not translate to dominance or whatsoever, otherwise conquistadors would have been stomped by the overwhelming masses of native americans.
Population decline does not mean extinction, especially so in the case of humans. Human populations through the history have jumped back and forth in numbers, including supposedly down to 1500 ppl during extremes of an ice age. Compared to historical jumps, our future correction is neither novel nor dramatic.
Fun thing about rightists is both these facts are public knowledge and not rocket science, but because of an indoctrination rightists actively choose to ignore inconvenient facts.