Shred I still think taking dinos to main land will just get us a cheesy godzilla/jp 2 rip and not much of a film I want to see. Where a problem with dinos dying of mysterious caauses and some washing up to mainland. As I saaid brings a good logical reason for igen and others to go back to island. What's the point in bring dinos/dinos showing up on mainlaand really have to story. Besides protect the humans and kill the dinos. Where my idea would bring in a save the dinos, a mystery to unrival, and then corp stealing if the twist is as I said a once old rival sneaking onto island for experiments.
But the thing is, that's repeating the exact same thing they already did with the last films, going to the island and escape it was used in all 3 JP films, another company being responsible for the problems that are happening, that was done in the first film too. Going to the island to find the cure of a disease or something like that also reminds me of a film that i don't remember the name that had some people catching sharks or something like that to find the cure of a flu.
And as i said in all my posts it wouldn't be TRex on big cities, it would be some different dinossaurs begining to appear all around the world, expecially flying and aquatic ones, that didn't appear enough in the last 3 films, which is normal considering the fliers were locked most of the time and because the characters were on earth, so the aquatic dinossaurs barelly made an appearance in Jurassic Park III.
And it doesn't have to be a complete "Lets kill the Dinoosaurs" movie, like Terry78 said not every escaped dinossaur has to be carnivore or attacks people, this worldwide event could also show the consequences of bringuing the past to the present.
They're also planing Jurassic Park IV to be the first of a new Trilogy, Joe Johnston even said "It's not about the dinosaur park anymore", if they made it set in the park again and refused to go out of the island then 4, 5 and 6 would only be repeating the same thing over and over again, which in my opinion isn't interesting or original. And after the ending of Jurassic Park III not using this seems like a really bad move, imagine if the studio didn't want James Cameron to use more than one Xenomorph in the alien sequels because it would make them less scary, the franchise has to evolve and bring something new to the table.