Hollywood studios usually don't like to delay getting their return on a $150 million investment by 5 months. So they must feel confident about this. May 8th release date (if it stays) is another sign of confidence. It shows that they think this movie (unlike most previous Trek movies) won't flame out after a couple of weeks, that it will appeal to non-trekkies and have enough legs to still be going very strong during the big Memorial Day weekend.