I believe the flaw in this thesis is that while white well-off progressives themselves aren’t reproducing, they are importing lots of non-white poor folks who are doing a fine job of increasing the number of Democrat voters.
Yes. And by importing voters, who they deliberately strive to keep ignorant as a mechanism to keep them voting “correctly” they both install themselves as the elite at the top of the foodchain (Vanguard?) while mitgating the risk of the “Alex P.Keaton” problem.