"No... I don't know. You know, when Crichton passed away, I sorta felt maybe that's it. Maybe that's a sign that we don't mess with it."

That's right--the death of the book's author is the reason not to do a fourth "Jurassic Park" film.  It's not that public interest in the project is non-existent; it's not that the sequels have been a series of diminishing returns at the box office.  It's that God sent the Reaper after Crichton so that the world would not have to endure a fourth "Jurassic Park" flick.  God wants dinosaurs to stay dead and the first three films are an abomination in the Lord's eyes.  Yes, Ms. Kennedy--it's "a sign".

Personally, at the rate remakes and relaunches are going, I don't think this franchise will stay dead.  In about five years, I imagine some producer full of hubris will take the DNA from the first three and then give life to a new "Jurassic Park" movie which will then destroy him but thankfully be contained to the island of California.