There is another report on the web with possible details (and therefore possible spoilers) about how William Shatner and Leonard Nimoy could fit into the 2016 Star Trek movie. See below for more details.
Shatner and Nimoy playing future alt Kirk and Spock?
There is another report discussing the possibility of William Shatner and Leonard Nimoy appearing in the 2016 Star Trek movie. William Shatner himself has often noted that one of the challenges of getting him into the JJ-verse movies is that his Kirk died in Star Trek: Generations (which itself takes place in a different timeline than the JJ movies). Today Badass Digest (source of the original report on Shatner and Nimoy’s possible role’s) has a follow-up report, citing ‘sources’ with more detail on how Nimoy and Shatner would be in the film, stating:
[Shatner’s] scene will have him meeting Chris Pine. Also in that scene: Zachary Quinto and Leonard Nimoy…it’ll be future alt-timeline Kirk and Spock. Basically the scene will have Kirk and Spock interacting with their future selves.
If true this would be a departure for Nimoy who has played the original Spock from the "prime" universe in both of JJ Abrams previous Star Trek films. So if true, Nimoy would be playing a different role, but it would solve the problem of how to get Shatner into the movie without resurrecting Kirk Prime.
TrekMovie cannot confirm or debunk the story. But so far both Nimoy and Shatner are talking about how they are open to appearing in the movie, so as Spock likes to say "there are always…possibilities."