I'd missed this. Farhad Manjoo, reporting last week at Slate:

If Amazon can send me stuff overnight for free without a distribution center nearby, it’s not hard to guess what it can do once it has lots of warehouses within driving distance of my house. Instead of surprising me by getting something to me the next day, I suspect that, over the next few years, next-day service will become its default shipping method on most of its items. Meanwhile it will offer same-day service as a cheap upgrade. For $5 extra, you can have that laptop waiting for you when you get home from work. Wouldn’t you take that deal?

As hard as it was for me to find Blu-rays today in a city as cine-centric as Austin...this would be the death knell. I don't know that I would drive across town if I could have it at my door tomorrow morning.