First, that's Kirk and McCoy (not Sulu) running through a field of red vegetation before jumping off the cliff into the ocean. Second, I didn't see a hand with a yellow sleeve in the shot that's evocative of Spock's death in TWOK. It looks like the sleeve of the black undershirt. Third, the woman screaming is Alice Eve, who is known for fact to be playing Carol Marcus, not Chapel. Fourth, McCoy doing the Vulcan salute as a dying joke? Really?
I don't think we know for sure which character on opposite sides of that glass is dying, if either. There's been a lot of speculation, but I'd put the odds near zero on that blue shirt belonging to McCoy and at nearly one hundred percent that it's Spock.