I read that Khan died of cancer, not natural causes?
"Natural causes" is the standard overall term for any cause of death that's of a medical nature rather than accidental or foul play. Otherwise, presumably, people would only say "of natural causes" when someone died "of old age," and even then there is usually some specific medical cause.
I liked Jurassic World more than most people did, but it could have still used a lot more Irrfan Khan.
I don't think an actor's death has hit me this hard since Philip Seymour Hoffman, and that's one I don't see myself ever getting really over, and I never even met the man.