Of course, this was born more out of necessity than intention, since the shark robot/puppet kept breaking down in the waters of Martha's Vineyard, where filming took place. However, history only remembers the result, not the malfunction.
However, Richard Dreyfyuss, who played shark expert Matt Hooper in the original, thinks that a re-release of the classic horror movie would make several floating yellow barrels full of money if a CGI shark was superimposed in place of the puppet.
“I think they should do it, it would be huge and it would open up the film to younger people,” Dreyfuss told Deadline. “Is that blasphemy? No, no, I don’t think so. The technology now could make the shark look as good as the rest of the movie.”
This will never, ever happen, mainly due to the fact that Steven Spielberg is against going back to his old movies and touching them up with CGI tweaks. The notorious replacement of the government agents' shotguns for walkie talkies in the 20th re-release of E.T. led to major regret on the filmmaker's part.
Then, there's that time George Lucas added a bunch of computer-generated additions to the original Star Wars trilogy when it was released on home video in the 1990s. This caused a lot of anger among purists, who said that they didn't ask for such additives. These were also the folks that later stated that Lucas didn't learn his lesson about overused CGI when the prequel movies came out.
No, Jaws will never have its practical shark replaced with a digital one, even if it was being done by some of the most knowledgable special effects wizards at ILM. To do so would be blasphemy of the highest order, on par with a sequel to Casablanca or whatever Son of the Mask was.