Historically that's what happens with any concentration of power and skill, things break when the founder/monarch dies. Look at Rome's endless civil wars and the countless Chinese dynasties.
Exception being when a capable successor is properly placed and accepted by the inner circle.
Does Linus have an "heir"?
I'm 100% with you on this. I also think that if Linus were to die today, the kernel would fall apart within 10 years.