I like Man of Tomorrow, or Superman: The Man of Tomorrow.
Or maybe just Superman, quite frankly. 1978 was a long time ago and in that time we've had several reboots, sequels and prequels with the same title (The Thing, Ghostbusters, etc.). It's not too soon to claim the title, especially if this film fixes the problems some fans have with this version of the character. And I think it could, if Vaughn is the director.