>>385547612
For me I think it's mostly haptics.
I don't NEED to IMAGINE the smell, and I don't necessarily need taste.
What would take VR to the next level is the ability to move realistically (so treadmill but perhaps more advanced, not sure what the answer is here) through the world and feel what I'm touching. If I pick up an apple, I'd like to feel it. I guess simulating the weight of the apple is going to be difficult to impossible, but I'd like to be able to run my fingers along the surface and feel the smooth skin of the apple. Or play a game like The Climb and actually feel the hard, rocky grips as I climb. Feel gunshots in Pavlov, etc.
I think Haptics is the easiest and best field to tackle to take VR to the next level. Smell is maybe next after that, and perhaps followed by taste. The hardest part will be balance, gravity and inertia. I think you would need an expensive and space-consuming harness system that can pick you up off the ground and toss you around (safely) that'd probably cost 5 digits and not be really viable for the average home user.