I wouldn't be surprised if they offered the role to Bieber. Not sure how he would be in the role as I have actually never heard him sing (that I know of) and am unaware of his acting creds. But he IS the right age and he would bring in the teeny boppers. Though they might have a hard time getting into an R rated flick, and then that sex scene would shock them. Stranger things have happened (NINE anyone?)
Of this batch of young men, if they look the right age for Melchior, they can't sing it. It is not a role that can be faked.
We all know Groff can sing it even if there are tiny crow's feet lurking around his eyes. Then again, if Lea Michele is up there repeating her role, Groff will look just fine. Too young in fact.
Meow.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher
If Lea gets the role of Wendla, I doubt she'd do it without Groff, especially considering how they are essentially attached at the hip and she has made it clear she loved doing the role with him.
Chord and Darren couldn't sing it or act it, Tveit and Stark are too old, Nick is a tossup and I'd not mind him doing it, same with Zac. I hated Hunter's Melchior on Broadway, so I'd rather not relived that on screen, so out of the options - I'd go with Groff.
"Anybody that goes to the theater, I think we’re all misfits, so we ended up on stage or in the audience.” --- Patti LuPone.
Literally none of these options are okay for this. I could see Aaron playing the Adult Male for sure. I would love to see Chris Colfer take on Ernst. I personally do not agree with a movie adaptation of this mainly because it is going to lose so much power from the stage to the screen. But we will see. As for Melchior, I say cast an unknown. Plus, they aren't going to look the correct age (Unless they get lucky in casting) because they will look for someone 18 or older so they can do the nudity.
"it is going to lose so much power from the stage to the screen"
"because they will look for someone 18 or older so they can do the nudity."
Stephen Daldry as director of the film might solve both of your concerns. His films can be very theatrical, and he could cast a 17 year old boy and wait until the teen's 18th birthday to film the nude scenes, as he did with THE READER.
^Since you mentioned The Reader I think David Kross would make a great Melchior if he can sing. He already showed everything in The Reader, and he's actually German isn't he?