Maybe, they thought, he played Wolverine, he's ageless! No but I agree. At the top of my head, I can't come up with someone (and that's with the idea that someone could ghost-sing for her like what they did with Rebecca Ferguson.

50yo - Laura Linney? Naomi Watts? (Google is my friend). Also, if I'm auditioning for this movie, I would be underwhelmed with Tightrope and the role in general.