But isn't that what is already supposed to happen? Presumably school authorities are trying to work out a useful curriculum, that they adjust from time to time?

Maybe a more useful discussion would be how to measure success and how to determine what is necessary? This "8th grade maths is enough" is a bit too handwavy.

I can actually imagine that there would not have to be as much focus on doing calculations on paper or in one's head, as everybody has a calculator ready at all times these days. As one example.