According to this blog post they planned to extend the ending of preview that was allowing users to run Office 2016 for free until October: https://blogs.office.com/2015/07/22/your-top-10-questions-about-office-2016-for-mac-answered/

Sounds perfect, this way people who don't want to sign up for Office as a SaaS can still use it and then pay for the software when it is released...

Unfortunately, many users have found that they never got around to extending the preview. According to one user that got in touch with Microsoft support, that blog post on Microsoft's official blog was inaccurate: https://s3.amazonaws.com/interesting-screenshots-wlm/Screen+Shot+2015-08-03+at+11.23.09+PM.png

Currently Mac users that had upgraded to Office 2016 are forced to either pay for a Microsoft Office Online subscription, or pray they can dig up the old CDs to reinstall Office 2011 which was released FIVE YEARS AGO