Even with additional liberal judges, the Supreme Court is unlikely to overturn Heller or McDonald. To do that, they would have to abandon the doctrine of stare decisis. That's very unlikely. No executive order or law can overturn those decisions.
A much more worrisome strategy is for our President and Senate to agree to be subject to the International Court. We've never done that. All it would take is for that to happen, and then have someone sue us in that court because our firearms laws are causing them problems. We would then have a treaty commitment to honor their decision. As I understand it, even that does not trump 2A, but it would be really messy for a while.
The most worrisome thing is a collapse of the US dollar. With that, we'd all be a LOT poorer. That $1200 balance you carry on your credit card would start to look like $12,000 instead. You wouldn't be able to shoot because your entire budget would be dedicated to food, shelter, and medicine. A couple of chickens in the back yard and a big garden would suddenly be an extremely attractive option, and some beans and rice done in a pressure cooker would look like a feast.
