Tom Corless just released a rumor where each Epcot Pavilion might have a Gardens Of Wonder Display, including topiaries used in the Flower & Garden Festival. This explains the greenery shown in the concept art of the D23 Expo.
In my opinion, Disney is also taking inspiration from Shanghai Disneyland’s Gardens Of Imagination. We will have to wait and see what Disney announces starting December 5th in the Disney Parks Blog.
Source:WDW News Today