Just speculation on my part but, as a fireworks lover, I'm looking forward to the replacement. Don't get me wrong, I loved Wishes and now love HEA. The new show will probably contain some of the same technology as HEA which would mean the construction of a replacement of some sort screen/globe which will be under construction and not in use until the new show starts in 2020. So what does that leave as a replacement. Fireworks! They can be shot off from different places and have the flexibility to change nightly around construction.
So, although I'll miss Illuminations, I'm sure I'll both the replacement and the new show.
PS does anyone know when Illuminations first debuted? I would swear it was there in 1992 on my honeymoon but maybe it was something else.