When they start talking about cabinet heads being in the line of succession it starts to sound like the Daily Mail UK describing the cousins of William and Harry.
The line of succession has never gone past the VP in usage. Always a first time but it would require very unusual circumstances.
Yeah it seems the line is succession angle is a bit of a stretch. A lot of crazy stuff would have to happen to get all the way to this position becoming POTUS.
Reminds me of the old movie Kind Hearts and Coronets.