I would say durable systems are what run the world. The code making up the components are not necessarily durable! Just like living cells die off but maintain the consistent identity of the overall organism, software systems often deal with an endless churn of dependencies and components without changing their overall functionality.

If you have a system of a dozen components with well defined interfaces, you could imagine an LLM rewriting and redeploying each component one at a time, without changing the observable properties of the system.