hmmmm, with such a massive incident (destroying Vulcan) in the timeline, how come the temporal division of Star Trek didn't do something? hell, in the episode 'Relativity' (Voyager) the temporal guys were out to stop just one ship from being destroyed. ...
hmmm got an idea for a script to put things right here
Why haven't the Department of Temporal Investigations fixed most of the botched time-travel shenanigans in Star Trek
? If you poke around you'll see that the timeline actually branched at 2233, when Nero first appears. At that point there is the original timeline and the new one created by his incursion. Think of a fork in the road.