UPS is a slow moving entity because of its enormous size and culture. Their delivery system was more or less handled manually until about 10 years ago. 15 years ago they were still using punch clocks for hourly workers. "Eventually" could mean 25-50 years from now.

I know that FedEx (and probably USP) are both very interested in flying big unmanned autonomous vehicles (cargo planes) between airports.

Fedex and UPS suffer from the innovator's dilemma which will make it hard for them to build the best drone service with the right business model because it means they'll lose money, sunk investments and jobs relative to their old business model.

Anyway, this is probably a field rich with patents and amazon with their acquisition of kiva robotics and their attraction as an employer in this field with this PR, will grab quite a few patents and make it quite hard for other companies to compete.

If you've ever worked with or for either of these companies you would know how "old school" they are. They can barely keep an autosorter running, I wouldn't expect them to be able to run a fleet of unmanned drones. Also I'm sure the union at UPS would have some feelings about losing jobs to robots.

Source: I worked for FedEx Smartpost/Ground IT for a few years. It was absolutely terrible.