I love how people want the movies to be exactly like the comics. *Rolls Eyes* 
 
They took the core elements of the Green Lantern mythos, and sewed something new and original from it. Why do you want to see a rehashing of the same stories you already know? Take bits and pieces of those old stories and make something new. Movies 2 and 3 should NOT be Sinestro Corps War and Blackest Night respectively. Don't shoehorn in the Antimatter Universe or the Blackest Night prophecy or the entire emotional spectrum. Star Sapphire and the original Predator could work. Atrocitus could work, but the Blue Lantern Corps, most of the Red Lantern Corps, and ESPECIALLY the Indigo Tribe could NOT fit into a movie, even if there's more than a trilogy. 
 
By all means, have Sinestro recruit a few more lanterns for his coup, but keep him as the only one with an actual Yellow Ring! That's why he would be a credible villain. Keep the focus in space, give more screen time to Kilowog and Tomar-Re, maybe a select few others and have them participate in the final battle with Sinestro's Squad. Put some emphasis on Hal's distance from Carol while he's in space. Set up Star Sapphire for the third movie. 
 
Have Star Sapphire in the third movie, maybe don't let Hal know it's Carol at first. Put in The Predator. Free Carol. 
 
THEN for a fourth OR instead for the third would be when Hal could start getting into the darker side of the corps. Bring in Atrocitus. He's just broken free from the Sciencells. Who is this mysterious baddie? What's that he's saying about the Guardians? Hal investigates. Hal uncovers the secrets of the Manhunters and the massacre of Sector 666. 3 or 4 movies in, now that Hal is in tune with the corps is the right time to have him gain doubts, not from the very beginning. 
 
ALTERNATIVELY Larfleeze could be used. Greedy being from the forbidden sectors storms across the universe to satiate his hunger. Although actually since he has an army of his constructs he could be the biggest of the movie villains yet, and potential for a 5th film if the others all go through. Or even just an alternative idea for the 3rd or 4th. The point is, Sinestro Corps is just too big for the second movie. Sinestro and a potential coup? That works. Even the Red Lantern Corps wouldn't be great for a movie. Atrocitus would be more credible mostly solo, especially if it worked out the way I suggested. But they should try to set him up on his own, try not to go too Red Lantern or else people will say it's too much like Sinestro, just another color to fight. The Predator works differently, and Larfleeze technically does too, so it works better. And out of all of those, Larfleeze would be the biggest threat. 
 
Finally, NO NO NO NO NO to Emerald Twilight. Yes, Emerald Twilight was epic and awesome. But this movie is trying to appeal to a mainstream audience to bring them in. Mainstream would not accept their big commendable superhero doing such a huge 180…. 
Scratch that, it MIGHT work. ONLY if Atrocitus AND Larfleeze get movies, because THEN Hal would have sufficient enough disgust for the Guardians for such a path to be even conceivable for him. That would be a good way to introduce a new lantern of Earth, probably Kyle. But A LOT of the story would have to be changed, but it MIGHT work.