Since "This isn't your father's Star Trek", why should the Borg be quartered in the same part of the galaxy as in "Daddy's" boring old Trek?
I think the idea of the new universe is that the only change is that Nero and then Spock time travelled to the 23rd C. Any changes are a ripple effect of those specific events and it's unlikely the Borg's location would be impacted.
But Spock could help Starfleet with some new 24th C tech to make their spaceships faster and get to the Borg more quickly.