The link in the OP includes links to a couple of Amazon papers on how they see drone operations working in shared airspace. Primarily high speed transit between 200 and 400 feet and localised slow speed movements below 200 feet. Looks like most drones would need sense and avoid technology as well as the ability to communicate with each other and ATC. Looks pretty challenging - but then a few years ago we thought driverless cars could never happen. Looking quite feasible now.
The sense and avoid challenge seems pretty difficult given the range of things they are trying to avoid - they talk about things ranging from balloons to cranes.
As a glider pilot who might, entirely legally, be hill soaring below hill top level on the edge of an urban environment, perhaps on a busy Amazon delivery route, I find the idea of drones sensing and avoiding me quite worrying!