Originally Posted by VM1138
How widely spread is Nero-tech, though? Khan helped them build the Vengeance, a totally secret project. I suppose they could extrapolate some tech from the wreckage, but I doubt the entirety of Starfleet is armed to the teeth with TNG-level tech in Star Trek 3.
I still think the Klingons will be the big baddies. Also, since they like re-spinning parts of the old movies, who wants to bet we get a full-blown Carol Marcus-Kirk relationship culminating with the Klingons killing Carol?
I also think the Klingons make a good choice because they will be a different threat. In Star Trek (09) we had a rogue villain. In Into Darkness we had two rogue villains. The Klingons could present an official, organized villain with the blessing of the Klingon Empire, which could expand the story.
I'd also like for them to factor into the exploration-side. Perhaps the Klingons are meddling with a Starfleet mission on a previously unknown-to-Starfleet planet? Thus, an intergalactic struggle between Starfleet and the Klingons culminating on (or over) the unknown frontier over the fate of some special civilization, which could keep the challenge intimate.
I think that full-on war with the Klingon Empire will certainly be the backdrop for the film, but I don't think it will be the extent of the plot. I think thorstone is right, something else will be present. A mutual threat (that serves as the main plot catalyst), which ultimately brings about peace and ends the war.