Oh I think there'll be enough businesses try it out and I reckon Google will dangle just enough of a carrot for their competitors to think seriously about whether or not to jump on board.
TBH I think it's more of a way to collect data on consumers rather than the stores. How does the average Joe provide feedback about the store - via their Google account. Instant verified real person profiled and stacked up against all other Google profiles to filter out spambot accounts, etc. Oh and map search behaviour to purchasing behaviour.
Google is literally bribing people with free purchase protection in exchange for details about their buying habits. Basically what they did to webmasters with Analytics & Adsense. That turned out well *cough* Panda *cough*! :)