I'm always cool

I know this is a joke but I wanna explain to non-americans, and some Americans, that it is nearly impossible for there not to be a president. Since 1947 the line of succession has been laid out. The only way in which the US wouldn't have a president is if every member of the Executive branch, including undersecretaries, and every member of both houses of congress were killed all at once. In the interim, this is all theory, the states would assume martial law and emergency elections would be held to replace congress who would then nominate a president to serve whatever is left of the term of the previous president. Hopefully after the term things would be able to go back to normal and elections could resume as they had before.