If providing the current set of GMail features (including price) is uneconomical for Google after support for under-13s is added (and, AFAIK, all of the externa

If providing the current set of GMail features (including price) is uneconomical for Google after support for under-13s is added (and, AFAIK, all of the external evidence we have suggests that it is), then you're making a distinction without a difference.