I would say that it would be easier to have a celebrity promote scuba than to have scuba make a celebrity. Koehler and Chatterton are a examples of how far a diver might be able to go in becoming a celebrity. Not far. On the other hand, celebrity is a self-fulfilling prophesy. Actors hire publicists to make sure people care about them. Taylor Swift goes to the gym and there is an army of photographers taking pictures. They are not there by accident. Lloyd Bridges is associated with diving because he was an actor cast as a diver. Jessica Alba was actress that scuba dove for a TV show.
The problem with making TV shows or movies centered around diving are that doing any show on the water is a dicey proposition. Filming is based on conditions beyond the control of crew. Storms, tides, currents and sinus infections can all derail production, not to mention the cost of cameras, lights, equipment and lets not forget the cost of insuring talent involved in the production.
Sea Hunt used a lot of stock footage and took advantage an unsophisticated viewership. Videos made today would need high production values, so filming lots of scenes in swimming pools and aquaria would not cut it. GoPro and YouTube might make some viral scuba celebrities as talented diver/cinematographers start finding a voice. It is much more likely that a TV production, (like Sea Hunt) would make the next household name in scuba and not the next great spear fisher. Maybe they can have "Celebrity Bug Divers" where we get to see Reese Witherspoon join Morgan Freeman Lobster diving on a ship wreck off Cape Ann. The closing scene would end with them having Gordon Ramsey cooking their catch for them*.
*Disclaimer: I know nothing about TV cooking shows, whether Witherspoon or Freeman scuba dive or have shellfish allergies.....