What I think might be kind of cool someday is a Supergirl story where there's no Superman and she's
the only Kryptonian on Earth. That would be kind of an interesting dynamic to explore-- where she's the one showing off all these fantastic new powers for the first time instead of her cousin, and where the first superbeing humans encounter is... a small teenage girl.
(Of course come to think of it, that was probably a story they DID do back in the crazy Silver Age era. lol)