As I recall, it wasn't actually the Hobus incident, which took place in the 24th century in Prime Universe, that split the timeline. It was Nero coming through the wormhole and destroying the Kelvin, creating the Kelvin timeline. That was the point of divergence.
As far the 23rd century of the Kelvin century is concerned, the Hobus incident is something that may or may not happen a hundred years in their future. At most, it's something Zachary Quinto's Spock is going to have to deal with when he's old and gray.![]()
So if Quinto-Spock (let's call him "Kelvin Timeline" or "KT Spock") prevents the Hobus supernova, perhaps with "new and improved red matter),does that restore the original timeline? I get a picture in my head of an ouroboros. Or does it merely create a "new" timeline which is identical to the TOS one? The mind gobbles.