"But then, ALL retail outlets will eventually go away except for boutiques and big box stores. There's really no need for anything in-between and such a business will always be less efficient than one which has no physical presence."
You may be right in terms of efficiency, but it makes for a shitty life if your town (like many already in the US) doesn't have retail stores.
"The only thing that depends on physical presence is impulse buying, where you get someone in your store and sell them crap they don't need."
Those of us who aren't sociopaths actually enjoy going to retail stores, and speaking with human beings in our community. It's a richer life than spending your life in front of a glowing screen.