The Plot of STAR TREK 2 should be...
Complete fanboy post. Apologies.
I'm sure this won't happen, but what I really want to see in STAR TREK 2 is:
Older Spock, realizing time won't rip apart if he tells the new crew about his timeline, spills about Khan. Khan, in this timeline, is still in suspended animation in his spaceship (The Botany Bay) drifting lost in space. So Kirk and crew decide to secure the ship before Khan can wake up, get crazy evil, kill Kirk's son and sort of briefly kill Spock.
(Older Spock's perspective allows us to trade not just on how big of a threat Khan was in his first appearance, but on the threat he turned into years later in Wrath of Khan.)
Meanwhile, the crew of a Klingon ship have also identified the Botany Bay, and they want to dissect Khan to learn more about genetic augmentation. The crew of the Klingon ship are sort of a Bizarro Enterprise, both in terms of casting (get Kal Pen to play a sword-wielding Klingon) and character/competency.
Basically, it's crew against crew in a tactical battle in the middle of a dangerous area of space, and the ticking time bomb is "What if Khan wakes up." Which of course he does, forcing the Enterprise and the Klingon crew to team up in the third act.
I figure the Klingons "beat" the Enterprise, "win" Khan, and then he wakes up, takes over their ship, kills half of them, and then the Enterprise have to work with the survivors to beat Khan.
STAR TREK 2 is in pre-production now, and will presumably not remotely resemble any of the above.