Jurassic World was the first to NOT star a member of the original cast (well, unless you count BD Wong). However, this is not the version of Jurassic Park 4 that was in the works just a few years ago. See, that one involved human-dinosaur hybrid soldiers.
While the movie didn't get TOO deep into pre-production, it did have a good amount of concept art worked up:
Written by John Sayles, the basic premise was that a company had engineered hyper-intelligent human-dinosaur hybrids that would act as commandoes to prevent a dinosaur invasion of the United States (since the ending of Jurassic Park III indicated the dinosaurs would eventually move past their original islands). The movie we actually got HAS retained an aspect of the original premise (sorta) in the super-hybrid dinosaur, but the overall "disaster at a functioning park" is more in line with the way Jurassic Park has traditionally worked.
So anyone hoping for dino-soldiers, keep your fingers crossed for Jurassic Park 5: Goin' Commando.