King Daniel wrote:
Ugh. It's just a nightmare of Spock's, where he saves his mother but the ship is destroyed. It tells us nothing new. Bleh!
False alarm, people. Go back to what you were doing.
Tut tut. It tells us that Spock is still suffering from guilt. It hints that perhaps the Elders or the Katric Arc could feature in the next movie. It could be hinting that Spock is still not overly comfortable with Kirk as Captain and feels that it's his responsibility to keep Kirk from stumbling and making a catastrophic mistake.
Could John Harrison be a human accidentally possessed by an angry Vulcan Elder's Katra (seems a bit too similar to the first movie to carry out another revenge plot though)?
It could be hinting at all sorts of lunatic possibilities. To quote Uhura, 'This isn't reality; this is fantasy!'