I've been thinking about this in connection to what Christopher L. Bennett establishes about time travel in his DTI novels: If someone were to travel back in time from the present of the new continuity to a point in the past before the arrival of the Narada, maybe change a couple of things slightly, and then return to their own time, how would it effect the original divergence point?
If you're going by the DTI books, it depends what method of time travel was used. Black holes branch off another reality, wheras other methods alter the existing timeline. I guess the changes before the divergence would affect both timelines.
The Narada incursion damaged local subspace, crushed warp trajectories and killed the ability of the universe to roll timeloops and split timelines. No more time travel, kids. The world ends when you run out of humpback whales.
I always liked this explanation. It helps me see that JJ Trek has not erased the old time line. We see the Mirror Universe as existing parallel to the Prime Universe without erasing anything. In Mirror Mirror Kirk et al. were able to go back and forth from the Prime Universe to the Mirror Universe without creating a new time line. the TNG episode showed that multiple parallel Universe exist simultaneously. The method of time travel will indicate where you go. I like the idea or concept that different modes of time travel will get you to different destinations.
I have actually wondered what will happen in the new reality when, 20+ years after STID, the Cetacean Probe comes to Earth, and someone has to go back in time to grab some humpback whales to take to the future.
^While it would be hilarious if Kirk et al. traveled into the past and ran into themselves, I personally subscribe to the theory that when you travel into the past you're traveling into a different timeline from the one in which you originated, which in this case would mean they'd travel into a past from which they hadn't attempted to borrow some whales yet.
They run up into their prime universe counterparts trying to take their own pair of humpback whales, and they are forced to conceal themselves from themselves. Authorities mistake nuChekov for Chekov Prime and arrest him, nuScotty resigns when Kirk refuses to prevent Scotty Prime from selling the transparent aluminium, Uhura is sent alone to negotiate with the Norwegians, and the two Spocks accidentally switch places, explaining how Spock Prime got working on all thrusters by the end of the TVH.
Spock Prime will just stand on a beach in San Fransico bay, hold up his iPod and play the whalesong from the end of STIV at full volume. Crisis averted.
Like Back to the Future Part II where Marty goes back to 1955. Something like that might actually be fun to watch if they could pull it off. They wouldn't recognize him because unlike the other characters, the new Chekov is actually a different person and wouldn't look like Chekov Prime.
I wasn't joking about that one. I really want to see Anton Yelchin's Chekov detained and questioned by 20th century US officials. Without a clue as to why, preferably. It was so unfair to transport him from the elevator and miss the chance to tease the police for a bit longer. Let's give them a third chance. We don't even need to see the prime crew, just arrest him.