Just the opposite. Source code is an artifact of executing the specification.

Our roles change. We no longer write code, but instead encode knowledge, which the LLM is incapable of learning.

Yes but considering a counterexample. You inherit a production codebase with scant documentation form someone else who is no longer around. In that case the source code ends up becoming the spec more or less. How would you use ensemble to extract the spec form an existing project?