there is another one application: realtime track could be very useful for green screen previsualisation of live human in 3d environment or the other side with real environment and vfx character like the troll in lord of the ring (this was made with motioncapture system but today it's sould be possible to do this with camera motion tracking)

I'm working in vfx industry and i'm waiting this feature with great excitation, i hope this will be used by the blender tracker as basis for 3d tracking (optical could be just used for tracking enhancement) because optical tracking alone doesn't work any time (during fast motion for example). This could be used to automatically detect element that move in the shot and separate them from the camera motion.
May be realtime optical camera tracking could be done by moving optical search zone of tracking points at his estimated position based on IMU measurement???
This could be a killer apps...