I'm actually working with technology right now that is going to be leading right into that synergy between cinema and gaming.
The company I work for invented a spherical camera that has 11 lenses (the base is where the 12th lens would be), all filming at the same time. We also have software that stitches all these views together, so when you're watching the playback, you use an standard game controller to rotate the view while it's playing, as if you're turning your own head. It's practically seamless.
So if you imagine a movie shot with this camera, where the viewer at home decides what they're looking at in any given moment, there are tons of possiblities with POV films that feature whodunnits, battle scenes, etc. Each time you watch it you can have a completely different experience. I'm sure the porn industry would love to get a hold of this as well, as they're usually at the forefront of any new tech developments.
Obviously this is the kind of thing that would only be viable with home entertainment. I don't see how you could make a film interactive in the theatrical format, unless you're having the audience vote on what they want to happen, which I think would make it difficult to get "lost" in what's on the screen. Because of that, I imagine regular movies are going to be around for quite some time.