Trackers mounted on feet can solve the problem of locomotion in vr. Take a look at “The Path of Greatest Resistance” ( http://store.steampowered.com/app/499400/The_Path_of_Greatest_Resistance/).
In this game you can walk in VR by moving your feet, but not only running in place, which is hard to sustain if you are not an athlete, if you have trackers just a slight movement is enough. (you need to select the beta “jogginsensitivity” to try this function)
no other VR game uses this system, although it would be the solution either in combination with a treadmill or without, the sense of movement is greatly enhanced, and motion sickness greatly reduced
Many games are recently abandoning teleport in favor of free movement with the Vive controller trackpad, my dream would be something that translates the movement of the feet into pressure, even just forwards, of the trackpad, to use trackers with any game with free movement supported