Granted, Barbra looks great and I think she can sing the score. After all, I'm assuming most of it will be done in a studio where she'll have multiple takes. It's still a hurdle to get past the first 20/30 minutes of the show with Barbra having young children. It's just a bit much. Maybe people will be able to suspend disbelief for the first bit of the show.
I'm more concerned with Barbra wanting to cast Gaga as Louise. Having watched the last season of American Horror Story, I found Gaga limited and downright stiff at times. She's not the worst actress in the world, but I don't see her pulling off Louise in any way shape or form. She'd probably give us a great strip montage and that's it.
Travolta, strangely enough, I have no issue with. I do think he's a very fine actor. Just watch some of his earlier films like Blow Out. He has an inherent likability that Herbie needs and, let's face it, anyone can sing Herbie.
Throw in a few fun divas to cameo as the strippers in You Gotta Get A Gimmick and it could be kinda fun.