Then write your code as if someone's going to throw production away - which generally means writing documentation (design docs, good commit messages, comments on the tricky parts of the code, API contracts between components, etc.), so that if someone thinks they want to to reimplement production, that decision can stand on its own merits.

All of the worst production systems I've worked with are systems where people are running code from many many years ago because they don't know what it does and are scared to touch it.

Write one to throw away, even - perhaps especially - if it goes into production. Write production to throw away.