For context, the first known permanent photograph using a scene from nature and a camera obscura was taken in 1825. Exposure time was 8 hours. Development of the daguerrotype culminated in 1837. The first known glass photographic negative dates from 1839.
Motion picture imaging came rather later. The zoetrope didn't become popular until 1860 or so, some 1,700 years after its invention, though the modern form dates to 1833.
Reportedly, those famous 1878 Eadweard Muybridge photographic series of horses in motion were taken with stereographic cameras. He even made a stereoscopic zoetrope to view them.
I can't be bothered to do citations, but an interested person could look at a book called "Stereoscopic Cinema and the Origins of 3-D Film, 1838-1952" by Ray Zone. Some other books and Wikipedia have information on the topic as well.
My point is that stereoscopic imaging has been around quite some time. It has just recently emerged from its infancy. Only with the advent of digital cameras, dynamic stereo-rigs, advanced processing software and digital projection has it become reasonably practical to shoot and project.
Since I can't stand wearing those glasses in a theater and two-camera beam-splitter rigs tend to be somewhat cumbersome, I'd say there is plenty of room for improvement.
I couldn't speak to the continued popularity of 3D with audiences, except to say that auto-stereoscopic cinemas will be welcomed.
Personally, I'm keen to watch "The Hobbit" projected in 3D at 48fps.
I also like 3D for dance. Dance is an inherently three dimensional form. I expect dance in 3D will look better projected at higher frame rates - many dance moves tend to move so fast that the eye can't really track the movements in depth at 24fps.
I'd be pretty excited about 3D for sports too; I might even start watching them.
I certainly look forward to more 3D music videos. I shoot music videos because there's a lot of freedom to break all the rules. This would be fun in 3D.
Most of all I want to see more films like "Coraline" which use stereo space in interesting ways as part of the storytelling. When filmmakers start thinking of stereography as a storytelling tool first and foremost, 3D will truly come into it's own.