Let's assume you get rid of the second amendment and totally ban civilian gun ownership in the US. No legal firearms other than for the police/military, full confiscation of guns, etc. Let's also assume the public is broadly supportive of this effort, and that there are not large black-market caches for sale.

I am arguing there will still be a significant number mass shootings/casualty events, political assassinations using a firearm, etc, and that the only way to effectively prevent them is to roll back most of the bill of rights.

The gun is a very old piece of technology and you do not need a sophisticated one to kill people effectively. Shinzo Abe was assassinated with a gun that could be described as primitive at best. Mangione used a 3dp firearm to kill the United Health CEO. Rebels in Myanmar are fighting the military junta with 3d printed small arms.

I am fundamentally arguing that the capacity of any one person has dramatically (100,000x) increased since the bill of rights was written, for better and for worse.

To be clear, I fully support the bill of rights and want to see it expanded. However, I reject the idea that simply eliminating the 2nd amendment and removing guns from civilian ownership can fix the underlying issues. I think you will see "casual" shootings and hopefully even mass shootings go down, but they will not go away and I expect they will still be higher than anywhere else in the world.