I'm not to sure? I think it would be something that people would be very interested in the first week, month, maybe even 6 months after they opened. Although, the excitement might diminish quickly. When a new iPhone comes out people flock to the store. But after the first 2 weeks it goes back to normal. Something similar might happen to Google Stores.
Unlike Apple, the majority Googles products have been integrated into retail stores for years now, and haven't had the one stop shop for all Googles products. One could argue that it would be easier to stop by their local phone provider to buy Googles products, as that is what everyone has been doing. Then again, Google is getting much more advance with the products they are creating. with Googles ChomeBook, the Glasses they are developing, and the Diver-less car they have been engineering, a Google store may be a better option, opposed to a variety of retail stores. I can't see Lens Crafter selling Googles glasses, and a car dealer ship offering Googles Diver-less technology.
But, It should be interesting. Google definitely has the funds to do it, and if they did open some stores, I would stop by. (Some food for thought. There is a difference between a few flag ship stores in major major cities, and retail sotres that would popup across the country.)