This wouldn't pass the SCOTUS history and tradition requirement and eventually training requirements, licensing, and even violent felons possessing guns (at least to some degree) will eventually be thrown out in court. But even if it won't hold up to history and tradition, at least you have some rational basis for skill requirements to prevent harm to others or shooting when you shouldn't. But keep in mind the vast majority of crimes are prevented by just carrying a gun or displaying it during a crime, which requires no shooting skill. Then most defensive shootings occur at very close ranges where little skill is needed. Then factor in hitting bystanders is very rare in reality. Then you realize that even a person with little shooting skills is very beneficial overall.
Coupled with real world stats on how many highly trained and certified "professionals" carrying firearms shoot, wound and/or kill innocent bystanders compared with private concealed carriers, one has to question the premise that requiring the same level of training for private individuals would make carrying firearms in public any safer. In other words, if training and certifications are what make the difference, wouldn't the stats be reversed?
I still believe most gun owners enjoy shooting and practice enough to be more than proficient. Shooting is not like driving a car. it's 1000 times less complicated, have much fewer rules and laws, and cost way less to get one. In fact, nowadays, anyone who is over 18, can pass the super-easy written test and the not-that-hard driving test can get a license and legally propel a 3,000 lb+ hunk of metal and other materials down the road at lethal speeds.
But for gun owners, we worry .... ?