I think there is room in the hobby for etailers. Not in animals, or any of the bread and butter dry goods, but in some of the high end equipment. People simply aren't willing to pay the money for a metal halide system that I would have to charge at my usual markup, and I don't have room on my shelf to carry items at that low of a margin. I don't have a problem with them selling calcium reactors, metal halide systems, computerized aquarium controllers and the like. In most cases there aren't enough people in a single geographic area to continually be able to sell them to make it a worthwile investment in inventory. And because of the lower overhead that those guys have it makes it easier for them to live on the smaller margins, which ultimately puts more equipment into the market and creates more customers for the retailers. I am strongly against etailers selling livestock, and I feel that the bread and butter dry goods that get sold (lower end skimmers, tank supplements, etc.) is a matter for the retialers to take up with their sales reps and regional wholesalers. Good stores do just fine living under the shadow of the big boxes, and I really don't see much difference between the two.
One problem that I see is that there is not a convenient distribution point for most of the higher end stuff, ie skimmers and lighting. High minimums, high price breaks, and large case packs require the retailer to sink a signifigant amount of cash into inventory to remain competitive because in many cases you have to order the products direct from the manufacturer. As opposed to most other dry goods where you can order a week to two week supply on a regular basis, and negotiate discounts based on overall volume.