Warning: The following contains dino-sized spoilers for Jurassic World: Fallen Kingdom!
At the end of Jurassic World: Fallen Kingdom, Maisie makes a crucial decision that Claire couldn't and, in an act of compassion, releases the dinosaurs from the mansion. The weight given to this act seems to indicate that it represents a massive shift in the natural order of the ecosystem established through millennia of evolution. I believe Owen states that 'there's no going back.' Yet it was just a couple dozen dinosaurs set free; has the Earth truly entered a new era and become a Jurassic World as Ian Malcolm warns, or is he just overreacting?
Heading in to Jurassic World: Fallen Kingdom, the characters were grappling with an important moral question: whether to save the dinosaurs that we created or allow nature to remedy that which human hubris hath wrought, allowing the creatures once again to go extinct. At the end of Fallen Kingdom, this moral dilemma is rendered irrelevant for the time being as the rescued dinosaurs are now out in the world, roaming wild and free for the first time. Once again, Ian Malcolm has proven prescient and the events of the film represent a crossing of the Rubicon. The toothpaste is out of the tube now and there is no going back with the dinosaurs after Jurassic World: Fallen Kingdom. Extinction is no longer a threat and the dinosaurs will no longer be contained to one small island. They are here to stay. Here's why.
The Dinosaurs Will Be Difficult To Track Down
We don't know exactly how many dinosaurs were "rescued" from Isla Nublar, but it seems like they couldn't number more than 100 at most. So, in theory, that amount should be easy to find in the wild and recapture. After all, it's not like a T-Rex will go unnoticed at a zoo or Blue will blend into suburbia. However, there are several factors that will make tracking and capturing these creatures difficult. We know that the trackers in the dinos work in perpetuity, but the system seemed like it could only be accessed from Isla Nublar, which is under a fresh coating of lava at present. Also there is no organization actively pursuing the dinosaurs and they could spread far and wide before the DPG or the government mobilizes. The survivors of the Lockwood estate incident probably don't know the exact count of the dinosaurs in the wild. Plus, if this series has proven anything, it's that dinosaurs are difficult to track, capture and kill.
The Island(s) Is Still There
We all saw Mount Sibo on Isla Nublar explode in Fallen Kingdom, killing countless dinosaurs in an absolutely heartbreaking scene. However, I struggle to believe that the volcano completely wiped out every dinosaur on the island. We saw dinosaurs fleeing into the sea, so is it not possible that any of them made it back to shore after the lava had subsided? Also was there no corner of the island that was untouched by the blast? There is also the fact that the Pterosaurs could have flown away to safety, to Costa Rica or perhaps Isla Sorna. The site B island has basically been ignored in the Jurassic World series but the DPG website indicates there was a drop in population on Isla Sorna and the remaining animals were transported to Isla Nublar. But even if that is true, the Pterosaurs could at least fly to that island temporarily during the explosion. The very assumption that both island's dinosaurs are completely extinct leaves room for a nasty surprise when some find a way to survive.