In the prime reality, Romulus is destroyed by a supernova in 2387. Spock created a red matter singularity, getting rid of the star, but sucking Spock and Nero in, sending Nero to alternate reality 2233, and Spock to 2258. In the alternate reality, the star going supernova hasn't happened (and possibly may not happen for a long time) so we currently don't know. It depends on what the alternate timeline's Spock does to help Romulus in the future and whether or not red matter is ever produced. They have almost 130 years to see if our Spock or Nero's attack would change all of that. If red matter is created, then Spock would still try to use it to save Romulus if he was still working on the reunification efforts. When Nero is born in the alternate reality, the turn of events would change.