Please explain. All the main actors are signed on to be back for any sequel. Or are you saying this just because you think he's not worthy?
I think what he's saying is that he thinks the "Space: the final frontier... " monologue may not be used in future films in any form. That Nimoy was the one to deliver the lines at the end of this movie hints at the words being still tied in a way to the prime universe / timeline -- Old Trek, in other words -- while any new stories on the big screen will be told in this alternate, New Trek universe / timeline. Leaving the words behind might be a choice by the filmmakers to underscore the idea that this is a different course we're traveling now, in a different Trek universe.
That thought crossed my mind, too, but I dismissed it. But if that
was their thinking in giving Nimoy the lines, I'd have to say I don't agree with the reasoning. Those words are supposed to be what Trek is about, in any universe.
And, in the context of the beauty shots of the Enterprise as Nimoy says those words at the end of the movie, it's almost as if he's introducing us to the new crew and telling us
their mission.