Correct me if I'm wrong, but my take on it, if you are still discussing Sustain (SMN pet heal) and not just finding flaws in each other's logic, is that now healers will have the responsibility to keep pets and such up. For example your fellow healer could keep an eye on your fairy too, while you also keep an eye on both your fairy and SMN's pet. That sort of dynamic doesn't seem far-fetched.