Figure that Amazon hasn't gone Brick-and-Mortar, because of the high entry costs. This lets them do it, on the cheap, with pre-existing infrastructure. Gives them virtual showrooms in high-traffic areas.
I'm sure that they won't be leaving all 4000+ stores open. But the ones in prime spots? Sure.
Plus they are probably planned to be service points rather than sales points, or only carry limited types of merchandise.
Still, it is a deviation from the business model. I’m still waiting to see how the fight between Fry’s and NewEgg resolves in the tech market. If I need something now, I go to Fry’s. If I want the best deal, I usually go to NewEgg.