I don't see the congress passing a national concealed carry law (for or against).
If it did, it would be subject to challenge, but I don't think the Tenth Amendment would carry the day. If a challenge succeeded, I think it would be because the concealed carry law was not based on one of the enumerated powers of the federal government in the constitution.
If a concealed carry law were based on one of the enumerated power, then it would be difficult to strike down. Of course, the congress can ban concealed carry in interstate commerce, as evidenced by the prohibition on a passenger's carrying any firearm (openly or concealed) into the passenger compartment of an airliner. And the congress could tie federal funding of various programs that pass money along to a state to a state's agreeing to pass and enforce a concealed carry law (just as it did with the Drive 55 legislation).