Who cares about the original keys? Sondheim has always been clear that he prefers actors who sing and not singers who can sort of act. Krakowski not only has a history with Sondheim (having played April in the 1995 COMPANY revival and recorded multiple of his songs), but she also shares Bernadette Peters' ability to seamlessly wring comedy out of the most banal lines one second and breaking your heart the next. Her sex appeal has nothing to do with the reasons she'd make a perfect Witch; she's one of the few stars who gets musical theatre and musical comedy and has the chops to pull it off. Who gives a f*ck whether she is singing in the original keys? It's so silly when people bring that up as a reason for not casting someone. We're lucky no one cared that Natasha Richardson didn't sound like Liza Minnelli, or that Angela Lansbury couldn't belt Mamma Rose like Ethel Merman.
Moving on... Gyllenhaal would make an ideal Baker. After SUNDAY, I'd be happy to see him play all the juicy male roles in Sondheim's canon, the Baker, Bobby, Sweeney, Fredrick, etc. Also, loving the idea of Jackie Hoffman as Jack's Mother, that'd be sublime.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"