As we all know Dwayne "The Rock" Johnson is playing Black Adam..But who we do not know is who will play his nemesis Shazam. Here is who I think should play Shazam .
Matt Bomer is an interesting choice considering he has very little movie (Although Bomer voiced Superman in "Superman Unbound") experience but has done a superb job on the White Collar. Many of people wanted Bomer to play Superman, Batman, Aquaman, etc. Basically it would be a good fit for Bomer to play Shazam and as well as a good move for DC to make fans happy.
Garrett Hedlund is another out of the box casting I would enjoy.He has the height (6'2") but would need to put some weight (200 pounds) to go heads up with The Rock. Hedlund should be ready to take on another lead (or co-lead) role once again as Shazam.
Jensen Ackles! yes he is another t.v. star but he would be as good as a fit as any.He has the ideal size to match up to The Rock and had previous relationships with DC being the voice of Red Hood and being Jason Teague in Smallville.I feel he has the talent to take on this role.
Jake Gyllenhaal would definitely be an interesting choice to say the least.Gyllenhaal upcoming movie Southpaw show the type of body he would need to be Shazam but he has the talent to pull off this role.
Scott Eastwood is an unproven but he has the build and look for Shazam (after a clean shave) if he can take a little after his father he should do just fine in this rule. who knows this could be his breakout movie.