Right at this time, with a critical Senate vote coming TOMORROW - there is a serious question about dedicating energy to a hypothetical with almost ZERO chance of ever happening.
For your suggestion of mandated firearm training in school to be considered, there would need to first be widespread acceptance of the need for such training. That is the reason I referenced cstone's post about procreation - and procreation leading to mandated sex education.
Do you really think the prerequisite of UNIVERSAL ACCEPTANCE that our youth need firearm training has a glimpse of a chance of happening?