Within five to seven years, I expect all movies out of Hollywood to be in 3-D,” Jeffrey Katzenberg predicted at the recent 3DX conference in Singapore.“In sound, we’ve gone from vinyl to 8-track to cassette to CD to digital,” the DreamWorks maven said. “The flat-screen movies of today are the equivalent of vinyl records.” If so, when it comes to live-action tentpoles, it seems as if most of Hollywood is still clinging to their turntables and LPs. Stereo 3-D is the rage in animation, but there have been no announcements of a Batman, Spider-Man, Pirates of the Caribbean or other existing or potential franchise in 3-D, other than James Cameron’s epic “Avatar” for Fox. Few studios and production companies have publicly embraced 3-D. But many are quietly investigating the format as they plan future tentpoles, wondering whether Cameron’s film will do for 3-D what “Toy Story” did for computer animation. The most obvious concern about 3-D is the unexpectedly slow transition of theaters to the d-cinema projectors it requires. Disney, though, is committed to 3-D, has several stereo titles on its slate and isn’t waiting for more theaters. For the Mouse House, says Walt Disney Studios Motion Picture Group prexy Mark Zoradi, the first question is, “Would this picture take advantage of 3-D?” “I think you have to have the visual need for it,” he says. “I wouldn’t expect to see a big, epic drama in 3-D or a straight comedy in 3-D.” He is in sync with many in the industry who see 3-D as an event-film format, as Technicolor was in the 1930s. Tentpoles are, however, event films, so the fit seems natural. Yet Walden Media’s exec VP of physical production, Doug Jones, who oversaw 3-D pic “Journey to the Center of the Earth” for the shingle, warns: “In production, you have to have one (picture) as a learning curve.” So far, only Cameron and his “Avatar” cohorts are on that learning curve at the tentpole level. “3-D has to be demystified,” says “Avatar’s” producer, Jon Landau. “You have to make sure the filmmaker is comfortable with it. I think there are now enough opportunities where people can go out and test the equipment.” That kind of testing is accelerating at technology vendors such as Pace Technologies, 3ality Digital and RealD. It isn’t just the filmmakers who need a comfort level, though. Many are asking about the added cost, especially for pics with lots of visual effects. “It’s the backend where everybody’s having a hard time, and there’s no standard way to do things,” Walden’s Jones says. Stereo means making the movie twice — once for each eye — so, in visual effects, labor-intensive tasks such as rotoscoping and compositing must be duplicated. Stereo pioneer Vince Pace routinely tells potential customers for his 3-D technology that going stereo adds roughly 20% to the negative cost of a movie. Jones, for his part, estimates that on a film with a lot of digital visual effects, the format brings a 20%-30% overall budget jump. With tentpole budgets already in the $250 million range, that’s a lot of extra cost, with no proof yet that a blockbuster like “Iron Man” would earn any additional money in 3-D. Many point to “Avatar” as the moment of truth for live-action 3-D. If it is a smash, others will follow. Then competitive pressures may make Katzenberg a prophet, because if Warner goes stereo with Batman, for example, how long can Sony keep Spider-Man flat?