I said this some time ago on another thread but thought it relevant to this discussion: Rivers of Light over at Animal Kingdom will be a good bellwether for a modern Disney nighttime show that (hopefully) doesn't feature characters or animated IP. If they can pull off a successful show over there, then I would feel a lot better about a replacement for RoE.
Any replacement show for Epcot that features existing Disney IP/characters is a non-starter. To lose RoE for a show that includes Frozen or Aladdin or any other animated nonsense would be a real punch to the gut.