All things are worth investigating. I think an Aquarium and yet another car museum is a very heavy lift. Here some basics on one of the more famous aquariums in the country, which I have visited in the past:
https://www.presstelegram.com/2021/0...ide-reopening/
Also depending on philanthropy on a forever basis will be a tough sell and unrealistic on an ongoing basis... you have to continually "Feed the Beast".
I think building on and leveraging our strengths is better, like the example of the DIA and the current auto design exhibit.
A strong, expanded Motown Museum deploying existing exhibits, like the Motown Exhibit displayed at The Ford in the past great interactive exhibits could be redeployed to a wide visitor audience.
DIA, African American Museum, Historical Museum, The Henry Ford Complex, & Auto Tours, Motown Museum, Belle Isle +, Auto Baron Estates, DSO, Pewabic...put the energy, time and limited resources into these gems. Expand programming, demographics, and fresh ideas.
As I said all things are worth exploring.