According to sources of the Financial Times, and corroborated by The Verge's own sources, Google has been talking to music labels about licensing deals for a subscription music service to launch in the third quarter. Play Music (then Google Music) has only been around since May of 2011, and only received notoriety when several major music labels finally signed on to sell music in the Play Store. If these new deals pan out, Google could be looking to offer a montlhy paid subscription music service for users that would prefer not to purchase individual tracks, with a free tier that offered unlimited play but with advertising.
If Google was able to extend its existing licenses to a subscription streaming model, it could take the likes of Spotify and Rdio head-on, furthering the amount of compelling content available in the Play Store. Details on the deals are sparse at this point, with the launch window still up in the air. The best indication right now is the third quarter of this year, but things could certainly change.