Fully immersive is a pretty fluid concept. If you are talking about full consciousness jack-in like Gibson's _Neuromancer_ or Vernor Vinge's _True Names_, I just don't see that being a reality any time soon, however I suspect that we are closer to a practical total immersion that you may suspect.
Audio and visuals are pretty much there, particularly if you want to spend the money. There are some questions about just how photorealistic ideal graphics should be. Type 'uncanny valley' into your favorite search engine for a bit on this.
As far as other senses go, taste is probably not too important, could could be dealt with. Olfactory could be easily enough attended to, but might be expensive and a bit potentially messy... really probably a question of how badly it was desired.
As for tactile, That is probably a bit closer than you might imagine. Elements of tactile response have been easily available for a long time. Back when joysticks were still common, the fanciest of them used force feedback, particularly with air combat simulators... I know other types of game controllers have some similar effects. There are expensive gaming seats with a bunch of reverb and vibration effects, and some even with various sorts of tilts to mimic variable G forces (these have been around for a while in professional flight simulators). Keep in mind that the whole area of tactile response is really all about how one tricks the brain. Also, I don't think that anyone seriously wants _total_ tactile immersion. When your character gets shot (or whatever) i don't think too many people are going to desire the excruciating pain of a gunshot wound.
As far as people getting totally immersed, involved in and consumed by their simulations, I think we are already there. even with just the basics of what we have now, people are all the time getting lost in their games and sims for hours or more at a time and losing track of 'the real world'. I don't think excessive technology is required there, at least not for a segment of the population.
I also question the premise that 'more immersive' necessarily implies more compelling. I mean maybe, and maybe for a meaningful segment of the market share. Further, I realize that I am likely a minority, marketwise, but just as a single example, I have grown up playing electronic and computer games, but the game I keep going back to and playing at least occasionally, is 1999's Unreal Tournament (albeit heavily patched, hacked and with all sorts of new, fan made code)... and there is still a significant online community for it. Also, I like bicycling on a nice day...
diogenesNY