And I'm content with considering the new movie to be in a parallel timeline to our own. Some things are similar, others not so similar. The new movie, as well as any who come after it, all can exist within their own timeline, without negating the one we have come to know over the past 40 years.
As such, perhaps in this parallel timeline, Kirk's first assignment was the Enterprise. We have no idea what the destruction of the USS Kelvin, did to the timeline that followed. Guess we'll find out in about 3 months.