President, Vice President, Speaker of the House, President Pro Tem of the Senate, and then the members of the Cabinet, beginning with the Secretary of State and taking the others in the order in which their Departments were created. The one who would survive, in the event of a nuclear destruction of Washington during a State of the Union address, would become President.
The Governors of the various states would then appoint replacement Senators, and call for immediate election of replacement Members of the House. The new President would nominate a new Vice President to be confirmed by the new Senate. He would also nominate a new Cabinet to be confirmed by the new Senate.
The new President would also order a retaliation that would reduce to a field of glass every enemy of the United States. A duplicate of the "football" would be with the Cabinet member who does NOT attend the SOTU.
All of this would be entirely in accord with both the Constitution of the United States, and its existing laws.
And that's the name of that tune.
Congressman Billybob
If I'm not mistaken, there is always one cabinet member who doesn't attend the SOTU address.