That would be interesting to know. One article [0] suggests that Internet sales account for a relatively small fraction of bike sales. I'm guessing that bigger threats to LBS's are big-box and general sporting goods stores. Used bikes also cut into new bike sales. Granted, this is all anecdotal and speculative on my part, but I know lots of people who have bought new bikes, and nobody who has bought a bike online. I know very few people who buy parts to use or install themselves, as opposed to getting them installed at a shop.

Another indication is when I look at bikes around town, I rarely see a brand that I don't recognize as being sold through normal retailers including big-box stores.

I think that online bike sales will be an uphill battle, because fit and comfort remain important, an very few people have the mechanical skill even to assemble a boxed bike. The skill to identify the correct size and type of part (even tires) and install it will continue to give local retailers an edge.

[0] Industry Overview 2014 - National Bicycle Dealers Association