The third park land acquisition, end of 2015. Dreamworks, spring, and summer 2016. Those two in conjunction created re evaluations of projects & timelines.
If anything changed the plans, it will be the third park land acquisition then. This is relatively recent chatter.
Also, of significance to Universal: 2018 is Jurassic Park's 25th anniversary.
I'm hopeful these plans stick - but not entirely optimistic. Jurassic is a weird property where Universal doesn't have full ownership (Amblin, for instance) nor claim to profits, and in the past it's made them hesitant about putting big money into it (it's also not as fan-centric as something like Harry Potter where the reward outweighs the 'risk')