The Yeti being broken is definitely part of a larger problem at the Animal Kingdom.
The addition of that attraction was a huge boost to attendance to a park that desperately needed it. The thing is, it can use another big attendance boost, but not with another E Ticket, it should be adding a C or D ticket every 2 years until that park gets to be a full day park.
We all know that the original expansion of that park should have happened in the first 5 years, and it would have included a comparable attraction to Everest in Dragon Tower, but that would have also been supplemented by smaller attractions in the area. Additionally, we were to have expected the Excavator Roller Coaster instead of DinoRama, and a more extravagant version of Kali River Rapids.
While it's my favorite park, it's becoming increasingly harder to defend, it really needs to take advantage of the expansion space it has available. Everest opened in 2006, and they should have a new major addition within 5 years of its opening. Clearly that's not happening, and this park needs it far more than any other park. Without this new addition, the park can't afford to close Expedition Everest for a prolong period of time.
I hope it gets destroyed by the Wizarding World of Harry Potter, but I think any attendance it takes away from Disney will be split between DHS and AK. DHS has Star Tours 2.0 in the works, and presumably the Monster's Inc Coaster right behind it.
The only thing that seems even remotely possible for the Animal Kingdom is a version of World of Color, but even that seems far fetched for many logistical reasons.
So I've ranted for quite some time without offering any solutions, so here goes.
Easier:
Bring back the Discovery River Boats, but actually add some details. It doesn't have to be a coming attractions/preview center of sorts for a Beastly Kingdom that isn't happening, but make it into a Jaws/Jungle Cruise type attraction with encounters of various Mythical Animals instead of a boat ride with nothing to see.
More in depth:
Put in a World of Color type show in the lagoon by Everest.
The question I have though: Do the Discovery River Boats ride on a track? If so, than presumably any water based show that requires a stage and viewing area would interfere with the current service area of the Discovery River Boats.