> The point is that previously, changing code in a major way might take months of refactoring.

> Now, the kinds of changes that were simply unrealistic before are now entirely realistic. A refactor/migration that would have taken 6 months before, you can now get a working version done in a day, and another few days of QA.

Significantly changing a system implementation is a function of understanding, not time.

Given a starting solution state being A and a desired functionality state of A', the tooling used to codify the A -> A` delta is largely irrelevant. Specifically, in order to successfully deliver major product realignment requires awareness of what exists currently and understanding of what needs to be.

Code is neither stone nor clay.

  When making software, remember that it is a snapshot of
  your understanding of the problem.  It states to all,
  including your future-self, your approach, clarity, and
  appropriateness of the solution for the problem at hand.

  Choose your statements wisely.