Any question that starts with "So, when you die..." is a strange question to ask someone you don't know personally, and probably a strange question to ask someone you do.
The short answer is that no one except Steven knows. To my knowledge it's never been addressed.
It could be asked of any software project with a single developer.
It's possible some provision exists for the source code to be released in such an event, but let's hope we never have to find out.
Bee excellent to each other...