FamilyTalk 550: any discount for *not* upgrading?

My wife and I are trying to decide whether to keep her iPhone 5S (upgraded last week) or "roll back" to her 5. At issue is whether there is a drop in the cost for her line if she doesn't upgrade. Currently, we pay $50/mo, but if we did a "buyer's remorse" and returned the iPhone 5S, would the line stay at $50 or would it drop in cost? I know the Mobile Share plan does, but this question is specifically about Family Talk. Anecdotal evidence is fine. 🙂