@LHoffman:
Threw a grenade all over TOS, TNG, DS9 and VOY; effectively making it so those events never occurred. The linear Star Trek timeline that progressed up to the point of Nemesis (2380) would never again be revisited in the form everyone understood, because those events now never happened.
Not necessarily, because it depends on which unprovable theory one chooses to believe about the fictional art of time travel. One of the competing theories is that there’s a single timeline and that each incursion into the past screws it up more and more. The alternate theory is that every incursion into the past creates branching timelines: the original intact one and a screwed-up new one, which exist in parallel from that moment forward. I don’t think Trek has ever formally committed itself on which theory it follows…if, indeed, it even sticks to following a single theory consistently, which it probably doesn’t.
In real-world terms, of course, the reason that the reboot films created a changed timeline, and the reason that ENT used the concept of the Temporal Cold War, was to allow any inconsistencies between the new stuff and the old stuff to be explained semi-rationally as being the result of timeline changes. It’s an explanation that will satisfy fans who don’t want Trek to be straightjacketed and which won’t satisfy fans who value consistency.
Ironically, one of the problems that Trek has run into over the decades – due to its sheer longevity – is that fictional Trek events that were set “in the future” from the point of view of when a particular episode was produced have been overtaken by events in the real world, meaning that later Trek series have had to revise the timing or the nature of those fictional events to take into account the fact that they never happened in real life. It’s a side effect of the peculiar relationship that Trek and real life have had with each other. (My favourite example is the fictional TOS starship Enterprise leading to the name Enterprise being given a real-world Space Shuttle prototype, which later shows up as a historical spacecraft in the fictional world of ST:TMP and ENT.)