Disagree.  There are some huge differences between century-ago mail order and today's online shopping.  First and foremost is the availability of resources to research the item before you buy it.  With old mail order, you had one picture in a catalog with a small description under it.  That was it.  As a result, shoppers had minimal confidence that the item was exactly what they thought it would be.  And it was a real pain (and costly) to return it.

Now with online shopping, there's far greater tools to view the item from many angles, far more in depth Q&A description, extensive consumer reviews, and often free and quick shipping and returns. 

That's not to say that there still aren't many items that people still prefer to buy in person.  But there are also many items that people PREFER just to buy online now because it's so easy (and often cheaper).  Online shopping won't totally kill brick & mortal, but it will continue to take much of it's market share.