We'll have to agree to disagree on that one. The person who learns his craft, has a depth of experience, and offers a full range of services is quite different from some guy who throws out a site with some pics and a price. The two business models are very different, and while some might do both, one does not beget the other.
One example Sports Authority, although you could argue they do not do "full service" of anything like we expect a LDS to do (and don't even sell SCUBA gear really). The retail chain and SportsAuthority.com are NOT even the same company. (the former merely licenses their name to the latter).
My LDS has an indoor pool for testing gear, does trips to the local lake, offers classes, lets me try on things, does air fills, etc. That all costs money. The internet guy has to cover none of that overhead, so sure he CAN sell it cheaper (often they don't actually DO it).
Local dive shops are not ever going to "evolve" into what they are not and do not need to become. Obviously, if you don't see value in what your local dive shop does, then don't buy there. But if you do, and you want them to treat you like a good customer, you have to be one. Dive shop owners are human beings too, and they appreciate loyalty.
That said...I order almost everything I can on-line. Books, appliances, electronics...the list is endless. Why? Best Buy and Walmart add no value whatsoever for me. I have been shopping Amazon since 1996. But again, there is no brick-and-mortar retailer of those items anywhere who can do anything but trade the item I want for my dollars. I don't want their advice, they can't service the product, and they won't let me take the item out of the box much less test it, so there's no point - there's no value add.
Local dive shops are a different species.