Night Kingdom as a separate facility is more than likely dead. However, elements from that concept can certainly be integrated into DAK.
Think of it this way, with this Nightastic promotion coming up, the other parks are getting some new addition, yet all DAK gets is extended hours. Colglazier, the new VP has a desire for the park to be open later, yet the inherent problem with later hours at DAK is lack of things to do after sundown.
DAK is all about adventure and while animals are certainly the biggest part of that, experiences such as zip lines and rock climbing could carry on that theme after the sun goes down. I can tell you that allowing guests to feed hippos or some other animal encounter along those lines probably never was in the cards as it conflicts with DAK's animal care philosophy.
We can probably speculate and guess what's in store for Harambe and Anandapur til we're blue in the face, but the way things have been going, we probably shouldn't count on anything until we get an official press release, however far away that may be.