Seussical is certainly unique in musical theater history. It went from being a massive flop and a bit of an industry laughingstock to being one of the most produced musicals in the country. And since it's largely being done by schools or TYA, it means that generations of kids are growing up being exposed to the show and likely developing attachment to it. I'm not sure if it will ever be taken "seriously" enough to rise above being seen as a show for young audiences, but who would've guessed at its trajectory?
"...everyone finally shut up, and the audience could enjoy the beginning of the Anatevka Pogram in peace."