I'm hoping they'd add back constellations somehow, so Celeste will be relevant again, other than being a store clerk for the museum. One of the exhibits on the second floor could be a planetarium that will show pictures of the constellations as you discover them in game. Maybe there could also be a chance of meteorites falling on the island on nights there are meteor showers, and you could collect them and donate the different types you discover to her too.
I'm also loving the idea of a minerals exhibit, and one for gyroids too.
Maybe separate the fish from the sealife exhibition? Or not. Depends how many new things they add in each category.
Definitely yes on a lizard/reptile exhibition. I would love that.
Botanical garden exhibition too! Submit one of every tree/flower/fruit/etc.
Maybe keep the empty rooms so players can do their own exhibits too, if they want.
Make the museum super huge, that'd be cool. More than two floors. Live exhibitions on first floor (insect, fish/sealife, reptile/lizard, botanical garden, gyroids). Inhanimate objects on the second (fossils, artworks, minerals, meteorites, player exhibit rooms). Planetarium on the third.