While trying to work out how to move quickly in VR without nausea I knocked up this sample in a couple of hours. To overcome motion sickness you would need the same hardware representation in the VR world for this to work.
Basically you are standing on a circular board which can tilt a full 360 but my theory is that you must have the same representation of the board inside VR so your body can learn that a leg movement left in the real world creates the leg movement left in the VR world and you strafe left, if you are moving forwards and rotate slightly left you start to turn left instead of strafing. Your body can learn to accept this much more naturally than other input systems. For example real skiing is quite hard to learn because it restricts your natural movement, it takes a long time to master. We need to find an input system that is fast to master and cheap to build.
To stop game developers from changing the speed or rotation of your input device in every game there should be a standard, maybe feet per second. Being consistent is a key aspect for this to succeed in VR. As you master full movement you can start to override and increase the motion speed in VR. Most games only have a walk or a run and blend very quickly between the two when using analog input. This system would need to make that much more accurate to allow greater control. Natural movement has many more levels of accelerate, sustain and decelerate than 2D/3D games offer.
The problem with thumb-stick motion is that there is very little link to what your body expects to happen and when it goes wrong its awful. A bit like the feeling you get when putting a car in first gear and expecting to move forwards when you accelerate but you have put it in reverse by mistake. The feeling is horrible and disorientating. I guess if you brute force yourself long enough you would build up a resistance to it (ye ole sea legs) but that really hampers early adoption.
I do not know if this concept would work as balance is a key element. Could a user move while shooting for example?