This case will cause a chilling effect but in a backward sort of way. The reality is that nobody is likely to be convicted in the way Crumbley was, because Crumbley was so unbelievably stupid it was literally criminal. So the only people who will be convicted under this precedent are the equally stupid.
But more intelligent parents will take note, get scared, and hopefully lock up their guns so their insane kids can’t use them to shoot up the school.