It has become a commonplace that a major cause of inequality in America is radical differences in parental resources per child. Affluent two-parent families can afford to send their only child to, say, SAT prep classes, while poor single welfare mothers can't afford such luxuries for their four children.
Thus, the demand for universal pre-K to have an impact on income inequality by 2076 by helping close the 30-million-word Nurture gap. (Of course, this purported difference of 30 million words heard by rich children over poor children is supposed to occur before age 4, so it's not clear how universal pre-K is supposed to solve that, but don't worry about that, it's heart is in the right place and that's all that counts.)
But, some worry that the affluent will still continue to invest more per capita in their limited number of children even if the government rounds up all the poor children for almost all their waking hours.
So, here's a suggestion for a national movement to fight inequality effectively: We must try to raise awareness of the idea that it is the moral duty of affluent and well-educated Americans to have more children, which would decrease the amount of resources of money and time these parents can devote to each child. Conversely, we must raise awareness of the need for the poor and the poorly educated to devote more of their limited resources to each child by having fewer children.
Assuming that Nurture 100% controls outcomes, this will lead to less inequality. Or, if you insist upon assuming that Nurture and Nature both influence outcomes, this would lead to somewhat more equality and quality of Americans. All else being equal, future generations would be smarter, harder-working, and less unequal.