I think it's premature to call this an end to brick and mortar. It seems to me that the likelier outcome is a hybridization of online and physical retail outlet

I think it's premature to call this an end to brick and mortar. It seems to me that the likelier outcome is a hybridization of online and physical retail outlets. People still want to buy their stuff in person and the cost of shipping is starting to wear on Amazon (fewer things qualify for free shipping and they've increased the minimum amount) which is probably why they're focused on optimizing shipping and adding physical stores to their approach. So the call for everything being online only is going to be proven a fantasy (hell, it already is a fantasy).