I never thought Tough to be a Bug made much sense for the theater in the tree of life. Sure, insects are an important part of the ecosystem, and getting close to the giant tree kind of makes you feel like you are shrinking.
But it always seemed to be a bit of a disconnect between Tough to be a Bug (specifically about the importance of insects) and the Tree of Life itself (a metaphor for the entire ecosystem).
It would be like if The Chinese Theater at DHS had a ride about just the importance of sound in movies, or if the ride in Spaceship Earth was about the agricultural products of Iowa.
For this reason, I think Zootopia could have the potential to be a better thematic fit, especially if it focuses on the different biomes.
I am cautiously optimistic!