There has been a lot of news out lately about drone delivery. Amazon has been testing their drones in Canada since being frustrated by the lack of progress in the US to get approval. German delivery firm DHL has launched a regular drone delivery service for the first time, nine months after it launched its “parcelcopter” research project in December 2013. Last year Google demonstrated its own drone-based delivery service, using a fixed-wing aircraft to deliver packages including chocolate bars, dog treats and cattle vaccines to farmers in the Australian outback. A San Francisco startup named QuiQui is currently testing drones that would deliver medicine and anything else you'd normally purchase at the pharmacy. China’s S.F. Express has revealed it already has a fleet of aircraft flying 500 parcels a day to remote areas, and it is now looking to double the capacity.
So really how viable will drone delivery be in the future?
Not even considering the cost viability we could look at the shear volume of drones in the sky. Last year when Amazon did a deal with the United States Postal Service it was reported that on an average Sunday in Seattle alone, 100 carriers delivered roughly 8,000 amazon packages. If you estimate that 1 drone delivers a package in 30 minutes from base to destination then in a day with 12 hours of sunlight (drones would not be permitted to fly at night according to the FAA) you could assume one drone being capable of making 24 deliveries in a day. That would require about 330 drones flying around Seattle to deliver those 8,000 packages. Now not all those packages mentioned would be capable of being delivered by a drone. However if the FAA were to clear these drone deliveries Amazon would not be the only company proposing such a service. You could expect to find Fedex, DHL, UPS, USPS etc. all entering the same space. There are currently roughly 1,162 parcel delivery companies in the US. This is even including all other delivery-based businesses such as Dominos Pizza or any number of startups that would enter the space. There would be tens of thousands of drones in the sky over a city at any one time.
Assuming this was the case, we could imagine many of the issues that would be associated with such a situation.
Having so many drones in the sky would present many safety issues. For one, they would be sharing this space with birds, which could cause a number of accidents. You could expect any number of drones experiencing mechanical failures and crashing to the ground potentially injuring someone. They could collide with each other. Radio range and interference could cause many issues with the proper functionality of the drones. Various forms of extreme weather could upset many aspects of drone flight delivery. You could also factor in the odd disturbed individual that would use all these flying drones as target practice. Dealing with these issues is not so straightforward as we are not even factoring in the necessary manpower required to fetch and repair downed drones.
Drones are not completely silent so with thousands of them you expect noise and visual pollution to become an issue with many.
It could be argued that many of these issues are currently experienced by traditional forms of delivery (car, truck, bicycle, plane) but drone delivery still presents a new batch to deal with. Wireless signals are far from perfect. If a signal were lost, hacked, or hijacked the drone would require additional human intervention to resolve the problem.
Drones would require designated delivery drop off locations, as it would not be viable to deliver to apartments of offices. Therefore, personnel would be required to complete the last leg of the delivery. Accounting for this and addition special insurances required, lost packages, various necessary operator licenses etc. it is still not clear that the potential productivity gains would translate into savings for any of these companies that present drones as a viable delivery method in the future.
I’m an not sure if those presenting these drone deliveries really believe that it is a viable delivery option or if this is well scripted hype but just looking at the numbers one can see how the disadvantages well out weight any potential productivity gains. 
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I disagree with your premise. You are assuming that drone delivery could only be successful as a replacement for all delivery, or that it is intended for that purpose. Certainly there are some procedures, legislations, and mechanical aspects that must be worked out to make it viable, but none of these is insurmountable.
It would begin as a special service which would be limited in range from a distribution hub, but worth some extra cost for someone in business who needed something now. Who would benefit the most from and invest in such a service, imagine a business working on a customer order in a machine shop and the last specific tool they had on hand just broke and they need another now. They would be the kind of customers to give this a shot.
As for designated landing sites or drop offs without landing, that can also be worked out in some specific cases. I think it unlikely someone living in an apartment would pay extra for drone delivery, although it could be accomplished at an apartment with a balcony without the drone landing (with proper packaging).
Bottom line if there is a market for it and it is profitable enough long term, someone will do it, the rest is just details.
Thanks for the feedback and voicing your views. Only time will tell what happens. I was just addressing lots of the hype that I saw regarding drones and delivery and how they were going to take over. There are very few in the air right now and already lots of problems with commercial aircraft among other things. I just wanted to layout some of the numbers which in doing so make it hard to imagine.
I appreciate your disagreement and where I do agree with you is that if there is a profitable business to be had then there will be but for the moment I just don't see many areas where that could be the case.