Hmm, not convinced...
Nice marketing stunt by Amazon. Maybe fun for the comnpany execs to thorw money at, but not convinced it will become reality anytime soon. For UAVs safety is everything; if any possible failure mode results in human injury or death then it is not acceptable. GPS is not a panacea; if it is used for safety critical flightpath control then it needs to be redundant, i.e. more than one receiver and it also needs receiver autonomous integrity monitoring (RAIM).
Imagine multitudes of these things flying down a street near you; it would be a disaster waiting to happen. What if one fails and then collides with another one, or several? Could it be absolutely guaranteed that they would stay away from airports and avoid people? I doubt it. Therefore, although the technology is fun and exciting, I would suspect the relevant regulatory bodies will make it almost impossible for such UAVs to operate in public airspace anytime soon.