I’ve been trying to wrap my brain around the big picture of all the changes made to the timeline in the new Star Trek movie. I know, I know, why bother? But that’s the way my brain works sometimes. I’d rather worry more about if this means the events of the time travel episodes that hadn’t happened yet (from the perspective of the characters in the film) still, in fact, happen, or if the ripple in the timeline goes both ways, than to worry about how I’m going to pay my rent on the 1st now that I’m not getting a GI Bill check for June. Entertainment is about escaping your life for a while, and I’d really like to escape mine for the summer while I’m (thus far) going to be unemployed (again).
The writers have stressed that the time travel in the film was quantum, rather than linear, which basically means they can do whatever they want to the timeline without “overwriting” the old one, because the act of traveling back in time created a new timeline parallel to the original. Great. Fine. But does that mean the new timeline also has copies of the time travelers from the original timeline while they’re in a shared past? Or do those people and their effect on history now get replaced by similar (if not identical) versions of their counterparts from this timeline? Or do those events just not happen at all now?
The writers stress their opinion that, changes aside, there’s a sort of “gravity” to events in the various Trek timelines (which is why we keep seeing certain people in various realities, even though histories are radically different). Effectively, some things are “destined” to happen, even if the chain of events leading to the key events differ slightly. Some of that was even written into the film (e.g. Kirk reprogramming the Kobayashi Maru, etc), though some scenes were dropped for various filmmaking concerns (e.g. Kirk meeting Carol Marcus, who in the original timeline would become the mother of his son).
Based on the evidence of the film, arguments can be made for any of those arguments… and more. Indeed, some of the changes even suggest that this is, in fact, not even the history of the timeline we already knew, but one that was nearly identical (though not exactly), as evidenced by the radically different stardate system used, though this could also be construed as evidence that the ripple in the timeline did, in fact, go both ways.
We may never know. Or not. They’re writing the sequel right now, after all.