The Little Mermaid gets all the credit, but it's more complicated than that.
Of course it does, that's what happens when the fans get all their Disney history FROM Disney. It's all skewed marketing PR and often only half the story. Disney doesn't want you to remember that
Honey, I Shrunk the Kids and
D*ck Tracy were bigger hits at the American box office than
Little Mermaid. It doesn't fit the narrative.
The real mermaid movie that saved Disney in the 80s was
Splash. After a few years of pushing the Disney brand with movies like
Watcher in the Woods,
Tex and
Never Cry Wolf, it was the first Touchstone release, and justified that Disney could branch out and make other successful movies outside of their key brand. It's why all the animators were thrown out of their own building in Burbank. It was movies with stars like Bette Middler who were paying the bills and Eisner was doing everything to make them happy. Until
An American Tail came out, he thought there were already enough animated movies made to keep the re-issue train running for a long time.
Cinderella justified doing animated features again, and it was slickly calculated to be as popular as possible and generate lots of revenue from ancillary business like record and sheet music sales. But
Alice in Wonderland the year after sucked away all the profits and demonstrated why Walt couldn't only rely on animated movies to keep the studio afloat. The success of
Treasure Island,
One Hour in Wonderland and other live-action content made for television and theatres are what did it in the 50s.
Really, the viablity of the studio has always been based on the success (or lack thereof) of their live-action movies. You can't operate a studio only putting out one movie a year (at most), you need several and Walt learned a long time ago the value of them, and Ron Miller found out too late how the studio limited itself in the 70s trying to make the same movie over, and over again.
It's also why Iger keeps pushing Marvel, Star Wars, Pirates etc. Something like
Wreck-It-Wralph 2 is not going to keep the lights on by itself.