While I'd love to see Nimoy's Spock again, unless a big part of this movie's plot has to do with Vulcan Reconstruction, I don't see there being much of a point for him to be in it.
I'm a huge TOS fan and I don't want to see Nimoy again and I definitely don't want him making comparative statements about what he saw in TOS and what is taking place in the new film. Pine, Quinto and the rest of the cast and crew need to succeed or fail on the quality of the universe they've created, not keep going back to the well.
The idea that the movie might open with the memorial service with the flyby being for Spock Prime (hey, he was old) had crossed my mind before the first nine minutes were revealed. It would've had everyone in one place at one time. A convenient target for a terrorist. Shortly after Kirk finishes his words and there's the flyby, the detonating starts. Actually, the sentimentalist in me thought, it would've been nice to see Spock Prime given the proper Starfleet sendoff he would've had in his universe. It also would've been better than how Berman treated Kirk.
Thing is, would Spock Prime really be that well known to warrant that kind of a memorial service? In the grand scheme of things, he's just another Vulcan to everyone else. Sure, the Enterprise crew knows who he really is, but he's likely keeping his actual identity a secret. A deleted scene from Trek XI implies he has no intention of telling Sarek who he is, so I doubt the other Vulcans or anyone at Starfleet is going to find out.