Zootopia maybe isn’t the most obvious choice for a new Splash Mountain, as there’s no real connection to the ride concept, but there are other reasons that this could potentially work.
First and foremost, at Disneyland in both Anaheim and Tokyo, Splash Mountain is located in the land called Critter Country, and so having the anthropomorphic animal characters both in the land and on the attraction would make a lot of sense.
Zootopia was a massive success at the box office, and while a new land is currently under construction at Shanghai Disneyland, the domestic parks have had little from the film beyond character appearances.