Marc Andreessen is directionally correct, but I think rather than software eating retail, it will be more a mobile enabled retail experience. Think of retail more like the Apple store model in the future with a mobile enabled shopping experience. Less inventory, more experience, much more known about the consumer while they are shopping and most importantly before they walk in the door.
The benefits are great - excellent social experience while buying goods, and the goods that you need right away are available, the rest can be delivered home. You can wrapper a shopping outing with food & entertainment with friends and super convenience through a tailored experience.
That is a much better future than buying every thing online from your computer.