Not necessarily. On the upside, the drones only weigh a few kilograms, compared to a tonne or two for a truck,
For dispatching a single rush package sure, it could be faster. But what does it do when it arrives? drop it on my front step where anyone can get it, or does it ring my bell, and politely hover at my door? Will it ensure i sign for it (typically rush packages are traceable)...
What if I'm in an office building? Does it drop it on the busy front steps, or does buzz in and drop it off at reception?... What if im a tenant in a skyrise the 30th floor?...does it take the elevator to the 35th floor?
Just doesn't make a lot of sense.
And for traditional daily bulk delivery; you are delivering along a street / superboxes etc... and the 1 ton truck probably carries half a ton of mail on its route, if not more.. how many drones will that take?
What is the drone range relative to a truck? What does the drone do on rainy days or windy days? How does it cope with snow? sleet? hail?
What happens when it malfunctions and has to land? (or crash)? Is my high priority rush delivery now sitting in someone's back yard or on their roof or in their swimming pool? Or up a tree? (that's what happens when you fly as the crow flies right? It may not be be next to a major road.) While a human postman is dispatched to find it..?
I may be missing something, but i just don't see where this makes sense in general. Maybe extremely cherry picked niches... but that's it.