The Lantern Corps is a cool concept.  

If you plan on letting people pick different corp colors, however, you're going to have to figure out a reason why all the players would team up and stay together, which may prove difficult.  Herding the cats, as it were, may be easier if you limit everyone to start out as a Green Lantern and possibly allow them to branch our to other corps colors during gameplay.  That way the players can build a camaraderie in-game and have more reason to reconnect when/if they transfer to another corps.

The other thing you'll need to nail down is what you want the players to be doing.  Figure out a main antagonist that will take the power of every player to defeat and then several lesser antagonists that can keep the players busy until they reach that ultimate climax.  Perhaps the first mission involves introducing the main antagonist and why it's a menacing threat and the subsequent missions are more focused on the Underbosses who are wrecking havoc across the galaxy that the players will have to go handle.

In any case, I'm interested, but it definitely needs to be developed more.