I'll admit that I agree with Bogdan that you can only do the "majestic awe of real dinos/calamity frees them to attack" scenario so many ways and times before it gets old. I actually saw JP3 for the first time last night, and, although it was serviceable, it was basically the same plot device as the first 2 films.
At the end of the 2nd movie, I was hoping it would end before what eventually became the T-Rex rampage in San Diego, because I thought it would be a nice progression for the third film to feature the inevitable arrival of the dinos to the civilized world. I felt it was premature ejaculation of sorts to have the T-Rex rampage and also signaled that the 3rd film would likely not feature such a scenario. As a result we ended up with a third film that mirrored the first 2..ragtag group of humans on the untamed island being pursued by dinos.
All that said I think the plotline proposed for JP4 is about as smooth a transition for the series as Jason X was to Friday the 13th. But something like Jason X is allowed to be self-aware of it's complete camp factor because it's coming from a movie series that has always dipped from the bottom of the barrel. If JP4 were to take itself seriously, it will be a laughing stock, and if it were to wink at the audience with regard to it's ridiculousness, it would compromise the deliberately realistic tone (all gymnastics aside) of the series.
It's just a fucking bad idea, although as I said, another island romp is probably just as lame. They need to do some more considering with regards to the conflict between these ancient animals and the modern world in which they have been brought back into. Cages and restraints aside, the isolated islands they are on aren't all that different from the ancient world in which they occupied. Why can't we see them interacting wholesale with the rest of the world that has advanced with time? Why not have cruise ships passing plesiosaurs in the ocean? Raptors scouring the suburbs? Packs of migrating stegosaurs on the interstate? Pterodactyls perched from skyscrapers? You could do all kinds of things, not unlike an alien invasion film or a monster flick, to make struggle between humans maintaining the status quo and dino's reestablishing dominance. It would be fucking cool. Why not, Spielberg? How hard would that be??