I have to figure that "the Spock that we've come to know" is Nimoy's Spock.
Since we've essentially been told that Nimoy Spock goes back in time and meets up with Quinto Spock, it doesn't really matter what happens to Nimoy Spock since, in theory, Quinto Spock will become the Spock we've come to know.
Abrams said months ago that one of the original characters dies in the film. So, if he's even remotely sincere about respecting canon, Nimoy Spock is the only person that he can be talking about.
It's neat and tidy, I suppose. But, it more or less insures that Nimoy could never appear in any other Trek films. At least, none that take place after Nemesis.
Not that they probably plan on doing any.