My point is you don't need an actual physical medium. This lies in manipulating the mind in ways that sleep does, and how this translates into mobile gaming is that at the flick of a switch, your mind would be able to enter into a dream like state or REM sleep, only with the difference that you are able to fully control your movements in the dream, also known as lucid dreaming. The key lies in being able to develop a mechanism that enables the mind to do this. I believe Dr. Allan Snyder's research into Savantism will help to shed light in this field. Although to practically apply my idea would no doubt be in the distant future.
How this translates to mobile is that with this neuro device in your mind, you can set the level of immersion you want in your brain, for a full immersion, it will be exactly like a dream like state. For a semi immersion, you will be left conscious of reality with my above mentioned projection. The key is, you won't have to be tied to physical mediums, and that in essence, is mobile.
I only have theories and doodles as to how be able to do this. But you must remember that Da Vinci's flight theory was only proved 450 years later. All he had too, were just doodles and theories. Some of his theories were impractical, but many are realities in today's age.
It took 450 years to prove his theory of flight, and only 65 years from that first flight to the first man on the moon. At the rate that technology is exponentially expanding, I still believe that breakthroughs in nanotechnology will keep Moore's law alive.
I put in lots of thought, this is why I removed the limitations to them.