Shatner will repose the role of Star Trek Uber Captain, James Tiberious Kirk. Still my favorite of the Captains, I have no idea how they are going to do this, except in more time travel mess. I don't mind time travel, I really don't, but it has to be handled with some degree of 'not shoe horning it into the plot in order to let an actor reprise a role.'
Terminator did a great job with Time Travel. There are other examples, but Star Trek hasn't been that good with it.
But they are surely aware of this and will hopefully make it work.
Because WILLIAM SHATNER IS AWESOME!!