A female Billy Flynn would be amazing, and I say this as someone who isn't too crazy about Chicago. But I'd love to see how the gender politics change when Billie Flynn does everything the same as Billy Flynn, and the only thing that changes is the gender.
I've spent years begging for a legitimate gender-swap of The Last Five Years because I want to know if people judge the characters' actions any differently when the genders of the people performing said actions are swapped.
Swapping the gender in any biographical jukebox musical is pretty difficult to justify as-is, but the one where it really doesn't work is Jersey Boys, because Frankie Valli's character is built around being a man with an unexpected and amazing falsetto. The show only works when his voice and his falsetto are what make him special. Any soprano could hit all of Frankie's notes and sing them well, so Frankie wouldn't be special anymore, and the show doesn't work. But now I'm picturing a female Bobby Darin and I'm kind of attached to it.
I want a drag queen as Dolly Levi again.
"See a picture of a woman wearing four years of confusion like a scar."