From the Constitution we already have the ability to have nationwide concealed carry if your state permits it.
Article 4 Section1
Full Faith and Credit shall be given in each State to the public Acts, Records, and judicial Proceedings of every other State
Act is any law passed by the state of record. So if in Ohio I have a concealed carry license then I can carry in any state. They have no right to interfere with that license or impose undo restrictions on my license. As long as I am following the rules put upon me by my state.