If you ever decide you want to migrate away from Postgres, it's because there's another platform that supports significant functionality that Postgres doesn't. Changing out the data tier is not a decision made on a whim.

If there is significant functionality we want to take advantage of in this new platform, then that means that we have to refactor anyway to use this, because by definition we either don't do it today, or we do it with an insufficient workaround in Postgres.

The migration necessitates large refactoring by its very justification.