Of course, Batman Begins, The Dark Knight and The Dark Knight Rises have redefined the Batman mythos, but then there's been Superman Returns, Green Lantern and Catwoman from the main DC stable which have been terrible, or from DC Vertigo's line there's been the woeful Constantine (aka HELLBLAZER to comics fans) and the faithful-but-oddly-received WATCHMEN (which I loved, but was torn to bits by a lot of critics) and V For Vendetta (which I also really liked, despite the Watchowski brothers' obsession with putting Bullet Time into everything).
DC hasn't had much luck aside from Batman, but that should hopefully change with MAN OF STEEL and usher in a new line of DC based superhero films which will in turn hopefully lead into a JUSTICE LEAGUE movie. The problem is, the team-up concept has been done so well by Marvel with the Avengers character films and finally AVENGERS ASSEMBLE (along with their next slew of hero movies) that JUSTICE LEAGUE (and the individual DC character films) will have to be very different indeed from the Marvel films in order to be seen as their own entity and not just knockoffs with more lame characters.
Batman is getting a reboot within a year. That sickens me, but it's necessary as a Nolan-style Batman would be awful as part of the Justice League. So, taking MAN OF STEEL as ground zero for the new DC universe, Warners are going to have to get cracking with some serious speed otherwise what interest remains will vanish altogether.
How could the Justice League save the DC movies? Here's how. I suggest Warners make the Justice League as their next project. No build-up movies other than Man of Steel. Just get Superman back in the game, then a kick-ass JUSTICE LEAGUE starring cast members who are committed to a solo movie for each of the characters, plus a sequel, and it may well generate enough interest in what is now an overcrowded genre in order to make good on WB's investments.
This could then lead into lucrative waters which would finally bring characters like the Flash, Hawkman and Hawkgirl, Aquaman, The Martian Manhunter and Wonder Woman to the big screen alongside Superman, Batman and (a different) Green Lantern. There are a number of ways each character could be handled, and with a strong approach to each one, a unique universe could be built (as long as it doesn't end up with someone trying to make CRISIS ON INFINITE EARTHS into a movie...).
So yeah, the Justice League could indeed save the day, but they're going to have to get there just in the nick of time. Thankfully, that's what superheroes are really rather good at.