This is already how a lot of this stuff works.
A manufacturer ships stuff to a DC, which ships stuff to a 3rd party pool provider, which ships stuff to a store, which then ships stuff to the customer (via "regular" mail).
Each step can be thought of as trading throughput for latency. Some manufacturers only ship things to the DC like once every few months (sometimes thousands of containers at a time), the DC to pools once a week (generally in tractor trailers), the pools to stores once a day (in either trailers, or delivery trucks), and the stores to customers multiple times a day (regular mail)
Adding another step on the end of that seems like the most likely "end goal" to me.
Get around the problem of the inefficient "last mile" of delivery by making the delivery truck a drone platform.