Interesting.. All the poor families out there would keep the kids in the house and working at sweatshops, and pop out multiple children to make a living. Here's the better question -- what happens if school, even secondary and grade levels, becomes elective? While you're at it, you can reduce the tax revenue - and enable the government to hand out nothing - and let it all be discretionary. Of course that wouldn't jive with poor folks who don't pay any worthwhile tax revenue anyway. Or do you think the state and federal govts should still collect an education tax and be in the job of allocating back to parents/schools as an intermediary to make sure everyone gets an education?
It could be worse. At one time Diane Feinstein wanted to tax as income the amount you would save by paying off your mortgage.
Check your US history - FDR did his own Mugabe impersonation back in the 1930s. When the Supreme Court made noises, he simply packed it with his own appointees and carried on with minor alterations.