According to Apple’s updated page about the company’s efforts to support the environment in honor of Earth Day 2016, references to products Apple explains the recycle process for are devices running MacOS, tvOS, iOS, and watchOS. As noted by 9to5Mac, OS X is no where to be found on the page.
This new leak is much more believable when compared to the framework name found earlier. Developers like to refer to OS X as macOS so their apps are easier to navigate and more organizable while programming. This would make sense for Apple themselves to do it in their software, however it’s strange for them to actually use this referral explicitly for the public to see/hear. And while it’s still unclear whether a rebranding is headed for OS X or not, it’s probably safe to say that this really could happen. But we’ll have to wait until June to see nonetheless.