There were plans from the Detroit Zoo to build an aquarium on the former Ford Auditorium site back in 2018. I believe that the mayor turned down the idea because he believe that site "could be put to better use". I believe he also said that he was concerned about families having to park and cross Jefferson which doesn't make sense since there was a parking garage next to the site or they could've integrated parking into the aquarium site. Also if they didn't like that site they could've moved it somewhere else along the riverfront.

In addition now that the Detroit Grand Prix is moving to Downtown it is likely that they'll use the GM surface lots as a staging area which means that area will likely not see development for some time.