I had the honor of meeting him in the guest hospitality suite of Dragoncon in Atlanta some years ago, where I was also a guest speaker. His personality in real life was exactly the same as his movie cameos - wise-cracking grandpa from New York. Due to his age, they have been doing cameo filming for several films at a time in recent years, to minimize travel. Live action shooting also happens 8-12 months before theater release. The CGI work comes after, because they have to synchronize it with the actors. So he may yet appear in several more films.