Yeah, haptic feedback is challenging. The thing that gets challenging in my opinion with 3rd party haptic sensors is a low latency integration. Also, there are no hardware standards that define performance/latency requirements for a good AR experience. All those things will contribute to designing haptic devices.
I saw a paper recently http://aut.researchgateway.ac.nz/handle/10292/9652 around a low cost haptic game controller, which interested me a lot. There might be clever ways to create alternate haptic feedback like hot or cold sensations when an object is grabbed or interacted with (https://www.sciencedaily.com/releases/2015/11/151110082541.h...).
Because AR itself is not mainstream yet, it is quite hard to figure out what is the right haptic feedback that feels natural. I am hoping this will evolve.
Even in AR you do not have haptic feedback, this to me is a critical component for a system to be truly adoptable outside of niche domains such as surgery, industrial processing etc.
I am sure many people are think of this. I have seen some research work out of the Media Lab at MIT trying to address this problem with deformable tables, likewise a Japanese group was doing air pressure haptics.
Could anyone working in this space comment on some state of the art stuff? And provide links? Thanks in advance.