Re: African genetics
One of the early observations is that there is a cline for genetics of africanized bees such that percentage declines in higher rainfall and/or colder winter areas. Texas tends to have fairly high percentage genetics in the West declining quite a bit in East Texas. I too got some BeeWeaver queens in 2015 and culled 2 at the end of the season keeping the best and gentlest for breeding.
To answer the original question, In one study, Africanized bees have about a 10 to 1 reproductive advantage over European lines. Also, a single Africanized drone can mate with a European queen and the resulting colony can be too hot to handle. Yes, the genetics get diluted over time, but never to the point of completely removing them from the gene pool and in favorable climates, always dominating European genetics.
NW Alabama, 50 years, 20 colonies and growing, sideliner, treatment free since 2005, 14 frame square Dadant broodnest