Google Play is the company's attempt to unify its myriad content offerings under a single banner, and further additions to the service could be on the way. The Help page for Google Play has empty sections for "Audio books" and "Magazines and journals", suggesting they may well be added to the Play store soon. Such a move would help bolster Play's credentials as a robust alternative to iTunes, which features audiobook downloads and support for magazine subscriptions through Newsstand.
Of course, Android users aren't without current options in either area. Providers like Audible are happy to sell you audiobooks regardless of your mobile operating system, and magazines have come to Android through Zinio and other apps. It's also worth noting that some magazines are available via Google Books, though the selection is mostly limited to older titles and isn't yet in the Play store. Google Play is all about simplifying and streamlining the content available on Google's services to date — hopefully the rebranding will translate to an expansion of content as well.