I thought Spielberg (who produces the franchise) and his entourage (Joe Johnston included) had let go of JP4 after Michael Crichton passed away... Not sure what to think of this.
Anyway, there were some rumors and concept pics flying around a couple weeks/months ago,
Spoiler:
according to which JP4 would broach the topic of bioengineering...something about mutated/genetically modified dinos being used for military warfare.
Sounded like an ocean of hogwash to me (if it's not a hoax then I should really start banging my head on the nearest wall I can find), even though, to be fair, in the original JP novel, Michael Crichton
did touch on the idea of dinosaurs being further genetically modified, for more...lucrative...purposes (IIRC it was a discussion between Dr. Wu and John Hammond, which never made it into Spielberg's movie, because he turned Hammond into a sympathetic character and not the greedy industry baron Michael Crichton envisioned him as). The Jurassic Park franchise is about Nature not letting itself being controlled and contained by the overconfident technology of man, not about man trying to "improve" Nature or whatever. If JP4 is all about mutants or machine gun-wielding dinos (remember
DinoRiders?), then it might be time to grab a pitchfork and start running towards Hollywood.
So they better have shredded the above idea and gone back to the "we must explore Isla Sorna/Nublar without getting CHOMPed on" theme.
Maybe we'll go back to Ian Malcolm this time, since JP3 had Dr. Grant as main character.