KD: This assertion is doubly FALSE. First: the children of the aboriginal peoples of Mexico will NOT [on average] marry into other races [and especially they will not (on average) marry Caucasians].
You couldn't be more wrong. Similar things were said of the Irish, Italians and eastern europeans when they immigrated in large waves. BTW, Hispanics were always considered Caucasian until the 70's.
Except, these groups successfully assimilated. The longest/largest study ever refutes your comparison.
Despite sixty years of political and legal battles to improve the education of Mexican Americans, they continue to have the lowest average education levels and the highest high school dropout rates among major ethnic and racial groups in the United States. ... However, leading analysts, apparently believing in the universality of assimilation, argue that this is the result of a large first and second generation population still adjusting to American society. ... These and other scholars predict that Mexican Americans will have the same levels of education and socioeconomic status as the dominant non-Hispanic white population by the fourth generation.... Sadly and directly in contradistinction to assimilation theory,the fourth generation differs the most from whites,
with a college completion rate of only 6 percent [compared to 35 percent for whites of that era]"