How long do you think it took Starfleet in the Abramsverse to design and build the USS Vengeance, which is a huge purpose built warship that dwarfs the Abrams-timeline Enterprise. I doubt the Vengeance's basic design was a direct result to the events in ST2009 since Nero's destruction of Vulcan in 2258 occurred only a year before ST Darkness took place in 2259, and taking less than a year to design a large, complex starship like the Vengeance from scratch to a complete and ready-for-service ship stretches plausibility. Supposedly Khan (who was revived by Section 31 under Admiral Marcus’s direction) helped design the Vengeance. I don't find it plausible Khan designed the Vengeance by himself since he would still have had late 20th century engineering knowledge when Section 31 revived him. Though, as seen as “Speed Seed” in the prime timeline, Khan was a quick learner and studied starfleet technical manuals, and Khan might have suggested refinements to the IMO already designed ship. Still, I doubt the basic design of the Vengeance was laid out by Khan and it's design was on Starfleet's drawing board for several years, and refined into a warship-oriented design by Marcus and his pursuit of a more military-oriented Starfleet. In the prime timeline it took almost 20 years from the Galaxy class to go from scratch to a commissioned in service-class. And I imagine it took a decade prior to 2259 to get the Vengeance off the drawing board and service-ready. It's also interesting the huge USS Vengeance took the opposite approach to the purpose-built warship concept, when compared to the small easy to build in quantity USS Defiant in the TNG-era prime universe.