Well, everything up unitl 1930 is the same. If and when the Nu-Kirk goes back through the Guardian of Forever, he might make some subtle changes to the time line that make things different from the timeline that Kirk Prime knew. Nu-Kirk might have created something inadvertantly in 1930 that makes everything in the Prime timeline become the J.J. universe. The interference might all have started a couple of centuries earlier, way back in 1930 before the Narada ever showed up.
Incorrect. Everything up to 2233 (Arrival of the Narada) is the same. It is all speculation what will or will not happen in the JJverse. In fact one should assume things will NOT happen the way they do in the Prime timeline as we obviously saw in the first new movie and which we will see as Khan appears in the new movie differently.
Fortunately, the head of brand management for Star Trek, who also runs licensing and who is basically in charge of Current canon for CBS was in my warehouse (I am the archivist for Star Trek for CBS) as I read your post and I addressed this with him. He said everything up to 2233 is the same in BOTH timelines and canon.
The whole point is the original "prime" timeline is intact. The new movie created a new timeline totally separate from the "prime" timeline, with the point of divergence being the arrival of the Narada. Things will happen differently in the new universe and obviously already have.
And then one can argue that any interference with the timeline before 2233 by the new universe will create a NEW alternate universe.