When TV started stealing business from cinema's, Hollywood's response was to use new technologies to give cinema patrons something TV's of the time couldn't. Hence, widescreen aspect ratios became widely adopted and, later on, the first wave of 3D, stereo, surround sound, etc.. TV technology stagnated and an equilibrium was formed that stood until home video came along and started disrupting things.
Today, the second wave of 3D is an attempt to tear people away from their hi-definition, audiophile-grade, surround-sound home-theaters and drag them back into cinemas (at double the normal ticket price). It will work, for at least a little while, until 3D becomes ubiquitous even amongst relatively cheap home video displays. At that point, 3D may very well die another death because Hollywood might not be willing to tolerate higher production costs (and limitations of the technology) for a gimmick that doesn't bring in enough extra cash. What will likely determine the longevity of 3D is if those costs will come down faster or slower than the sales-boost tapers off!
The next obvious step for viewer immersion is virtual reality. If VR headsets such as the Oculus Rift or what Valve has been secretly working on take off in the next few years and develop a large enough user-base, there's a remote chance that we might see some movies developed for them. Cinema's might also introduce VR rooms, making Hollywood investment in VR films more likely. These might be entirely on-the-fly rendered machinema that allow users to walk around freely inside the film, or pre-rendered films that place the viewer on a rail with only the ability to move their head to look around. Gimicky, yes. Highly unlikely to replace traditional film, yes. It could happen though, as one more way to boost sales.