That sounds pretty cool, except I was hoping for something a bit more proactive instead of reactive. A HoT wouldn't be able to save a teammate from certain death the way a shield or barrier skill would. That's honestly the BEST thing about skills like Cover, Intervention, The Blackest Night, and (to a certain extent) Divine Veil. You can see that someone is about to die, and try doing something about it.

A heal over time would just get overwritten by healers. I really hope there's more to it than just that.