It's not just a different timeline but a different universe as well. It would be like trying to merge the Mirror Universe with the Prime Universe--both have different and similar histories.
Although some scientists believe that "the Big Bang" that created our universe was the result of the membranes of two earlier universes colliding. A similar thing could happen if the Abramsverse and the Prime Universe should converge--it could simply create yet another universe that will produce yet another James T. Kirk and the Starship Enterprise.
Parallel universes and alternate timelines/realities--love 'em or hate 'em--but they keep going and going and going...
Free your mind, and the rest will follow.