The first premise is that in the future people will care about reproduction less. As an argument, fertility rates are negatively correlated with technological advancement. To the point where in many countries except for immigration the population is decreasing. Some projections estimate that Earth population will stabilize and somewhat decrease in the future (at least relative to the maximum, if not to todays numbers).
The second premise is that we’ll live longer. Again, life expectancy is increasing. We may or may not hit some ceiling of maximum life expectancy, there is no known reason why we couldn’s stave off ageing completely.
The third assumption is that we either don’t go digital (though I think we will) or that we don’t go into unbounded population explosion (at least on this planet).
The net result would be that there’ll be less children per generation, maybe significantly so.
This could lead to a change in attitudes towards their education. No doubt, now people say the value their children’s education and they worry about it. But anyway, kids get packed into classes of 20+ people, taught mostly the same way, and advance throught grades regardless of whether they learn anything. I’m not saying the schools are doing everything wrong. Maybe they are the best we could get given how much resources we devote to the task. The question is, what could we get if we devoted the same, but there were ten or hundred times less children?
David Labaree distinguishes three conflicting aspects of education: democratic equality, social efficiency and social mobility. That is creating competent, preferably equal, citizens, preparing the most capable workforce, and allowing children/people to learn as much as they can. If there is only one kid in the school threre’ll be no need for trade-offs. He/she will be a special project for each teacher. So presumably the kid will be taught the best possible way. Though being the only kid might be not optimal. Peers might improve socialization, add some competitive motivational pressure, or just make the process more fun.
In summary, if more resources are devoted to the task, quite naturally the outcome will be better. Whether the educational outcomes will be significantly better, the time will tell.