I can't watch the video right now, but even if this was a surprise for Hayward, I can't imagine he is devastated. Kyrie is currently able to start the season healthy, he is younger, has more potential to improve (as a four-time all star), and has had considerable more success at 25 than IT at 28.
IT may have been more 'fun' to play with for Hayward, but the Celtics' ceiling just went up with this trade and if Hayward's ultimate goal is to win a championship, then he should be ecstatic that Danny is still trying to improve the team even after his [Hayward's) signing.
They also appeared to have solid camaraderie during the press conference. I can't imagine this is a legitimate concern, unless Hayward genuinely dislikes Kyrie as a person - which seems doubtful.