John Mueller mentioned it in a Google Hangout recently, but it remains to be seen whether this was just him cleverly deflecting a question or actually opening a window. The full quote and news is on Search Engine Land and there's a forum discussion on SEO Chat.
It could be neat, and I know some webmasters would love to see it. As ThomasHarvey says in the above thread, "For ecommerce platforms schema should be the default anyway, it makes the user experience much better..." So it might even improve the shape of Google SERPs by encouraging a certain behavior. But it's just a rumor at this point - worth watching the hangout to get the full context, and deciding from there whether it's bollocks or not!