Why She Could Do It: While less well-known than some of these names, Mara was in the running to play Catwoman in "The Dark Knight Rises," so has experience with this kind of secretive, high-profile casting run-off. Plus she shares DNA with sister Rooney Mara, who's already won out one of the most competitive races in recent memory, landing the lead in "The Girl With The Dragon Tattoo." Also has roughly the same name as Holmes, which makes it easier for Cruise to remember who he's supposed to namecheck while jumping on sofas.
Why She Might Not: Once dated McG. That's got to be a hard thing for any future boyfriends to come to terms with.
Why She Could Do It: Like Holmes, the star of "The West Wing" and "Mad Men" started in TV, but is making increasing inroads into the movie world. Crucially, she's also already a Scientologist, so is familiar with the religion's quirky customs like not making sounds during during childbirth, and being imprisoned on cruise ships. Peggy Olsen quitting Sterling Cooper Draper Pryce may have been an early hint of where Olsen's career was heading.
Why She Might Not: She criticized ex-husband Fred Armisen, saying "He's so great at doing impersonations. But the greatest impersonation he does is that of a normal person." This worryingly suggests an outspoken quality, and also ability to determine when an actor is pretending to be a normal person.
Why He Could Do It: As shown in the gonzo mock-doc "I'm Still Here," he has prior experience of leading a fake life and going into semi-retirement. He recently worked with previous Cruise collaborator Paul Thomas Anderson on "The Master," so an introduction should be easy to arrange, and that film revolves around Scientology, so he should know what he'd be getting into. Also, is a man.
Why He Might Not: Nope, can't really see a problem with this one.
Honorable Mentions: Recent Cruise co-stars include Paula Patton, Julianne Hough, Malin Akerman, Cameron Diaz, Rosamund Pike, Andrea Riseborough, Olga Kurylenko and Melissa Leo (who is more age-appropriate than others, which persumably rules her out), and any of them might be wooed for a return engagement. Meanwhile Jessica Chastain, Hayley Atwell and Alexa Davalos were all in the running for parts in recent Cruise movies, and Emily Blunt is starring with the actor in "All You Need Is Kill," so she should probably be on her guard.
Scarlett Johansson was in the running for the gig before Katie Holmes got it: the actress seemingly rejected Scientology at the time, but may be more open to these days. Elizabeth Olsen would ordinarily be a good choice, but showed that she's capable of escaping from weird communes in "Martha Marcy May Marlene." Oh, and Vanessa Paradis is available these days too. Plus one of the Fannings is legal now, right?
- With thanks to RP, Kevin Jagernauth and Jessica Kiang