Why he should be cast: He looks the closest to C.C. Beck's artwork as any actor can be. His role in "Dallas" shows he has dramatic acting chops, and his role in "John Tucker Must Die" shows he can do comedy.
Why he should not get cast: He's only 5'9". With Johnson's Black Adam at 6'4", he's sadly just too short.
Conclusion: A long shot at best, if he's even considered.
Why he should be cast: He's a talented actor. He looks the role. At 6' he's not as big as Johnson, but still bigger than Metcalfe. He was Christopher Nolan's hand picked successor to the role of Batman, and he's good friends with Christian Bale.
Why he should not get cast: At 6', he still might be considered too short. Also he has had some drug problems in the past. The actor playing the Big Red Cheese needs to live up to a moral code not unlike that which Clayton Moore, of the Lone Ranger, and Jackson Bostwick, the Captain Marvel of the 1970s, lived by.
Conclusion: A dark horse. Don't count him out, but don't bet on him either.
Why he should be cast: He looks the role, and at 6'7" he would tower over Johnson.
Why he should not get cast: He's Colossus in the X-Men franchise, and while not a major role in those movies, and a supporting player in the Twilight Saga, that brings up the point he may not have the acting chops to be the lead in a movie and hold up against Johnson's charisma.
Conclusion: He will get called in for an interview and might even make it to a screen test.
Owain YeomanWhy he should be cast: He's a good actor, and at 6'3", a good match for Johnson.
Why he should not get cast: He doesn't quite have the right look, and he's known as a TV actor, and in his late 30s, may be too much of a risk to build a franchise around him.
Conclusion: He might get an interview.
(UPDATE: Yeoman has been cast in the Supergirl TV series, taking him out of consideration for Captain Marvel.)
Why he should be cast: He's a movie star who can do action, drama and comedy. At 6'1", while still not up to Johnson's height, he has the charisma to make it work.Why he won't get cast: He signed on to play Gambit in the X-Men movies. It's doubtful there may be an actual "no compete" clause in his contract, but it's even more doubtful he'll jump over to DC.
Conclusion: New Line won't even attempt to get him.
Why he should be cast: He was almost Superman and almost Batman. His build can rival Johnson's.
Why he should not get cast: He doesn't really fit the role, and just because he lost out to two other superheroes doesn't mean he should automatically be up for all superhero roles.
Conclusion: He might be considered early in, but won't get called in for an interview or screen test.
(UPDATE: Manganiello has been cast as Deathstroke the Terminator in Ben Affleck's solo Batman movie, taking him out of consideration for Captain Marvel.)
Why he should be cast: he's popular with the girls, and would draw them in to see the movie. He was rumored for Batman, but I think that was just PR on his part.
Why he should not get cast: At 6', he might not be big enough to go against Johnson, and he might not have the screen presence. He was on "7th Heaven"... come on!
Conclusion: I'd like to say "little chance", but... I just don't know. Off beat enough New Line might go for him.
(UPDATE: Hoechlin has been cast as Superman in season 2 of Supergirl, taking him out of consideration for Captain Marvel.)
Why he should be cast: he is generating a lot of fan support, but I personally don't see him as right for the role.
Why he should not be cast: although tall at 6'5", he is on the thin side. He has yet to prove himself, as The Lone Ranger was a dud, and The Man From UNCLE is getting mixed advance word of mouth.
Conclusion: He just seems a little too dull, and not enough charisma to carry the role and the film.
Why he should be cast: like Hammer, he is getting a swell of online fan support. Looks the role and openly professed interest through social media.
Why he should not be cast: best known for playing Aquaman on "Smallville". Hasn't really broken through beyond a supporting player status.
Conclusion: A better choice than Hammer, Yeoman, or Hoechlin, but still, maybe not right for a big screen film. Perhaps better suited if this were to be a TV production.
Why he should be cast: an outside-of-the-box choice considering he's the original TV Hulk's son, but, at 6'2" he has the looks, the muscle, and most importantly, he has acting talent.
Why he should not get cast: no real reason, other than possibly his link to Marvel-Disney via his father.
Conclusion: He should definitely make it to the final casting cut.
Derek ThelerWhy he should be cast: He has great charisma, and an innocent, big heart quality to him that would be perfect for the World's Mightiest Mortal, without delving into full blown "Big"/"Freaky Friday" territory. At 6'5" he could go toe to toe with Johnson. Although he's primarily a TV actor, he's young enough that the jump to the big screen is very probable.
Why he should not get cast: he's considered an unknown, but that could play to his benefit.
Conclusion: If I were a casting director, Theler is the one I would give the most serious consideration to.
(UPDATE: Theler has been cast as Marvel Comics' Mister Immortal in the New Warriors TV series, severely reducing his chances he'll be cast as Captain Marvel. This could be a crippling blow to the casting process and to the movie.)