Man of Steel's not beating either Iron Man 3 or Star Trek: Into Darkness domestically, though it might beat Star Trek worldwide.
If Man of Steel does Amazing Spider-Man numbers, WB should be tickled pink. That would make it the third highest grossing unadjusted franchise kick off in comic book movie history, behind Avengers (which no film is going to outgross until at least 2015 when A2, JLA, Star Wars and Avatar 2 drop) and the original Spider-Man.
The truth is, Superman is a bit of a fallen hero. 35 years ago, Superman: The Movie had ticket sales that roughly equated to $1 Billion worldwide in 2013, but Superman stock was higher back then.
Superman had a rough 90s. After 50 years of being unquestionably the top superhero in the world, he (and a lot of other popular golden age heroes like Wonder Woman and Captain America) took a hit in popularity for being a bit too wholesome for the Nirvana generation. The 00s weren't as disastrous for him, but there was Superman Returns, a film met with mediocre reception.
If Man of Steel is good, it will re-establish the character for this decade, but I think it will take at least one more film before we see a Superman "pop culture event" on the level of Superman: The Movie, Spider-Man, The Dark Knight, or The Avengers.