Amazon, with all of its technological and operations might, is pathetically terrible at their own last mile delivery operations (I'm going to discount them hauling trailers from distribution centers to USPS sort facilities; anyone can do that). To displace UPS and Fedex, you would require immense amounts of capital for your delivery network, and staff properly compensated and treated well for quality work (ie a union or benefits of sufficient quality, a union isn't required).

Arm chair "logistics experts" should go sling packages for a few weeks to see what it takes to compete with real operations before declaring existing operations dead if they don't "disrupt themselves". UPS, Fedex, and USPS aren't going anywhere.