We knew this was coming, although it was announced back in September 2015 so I would imagine a lot of people have forgotten all about it, but as from 1st March 2017 your users will no longer be able to download the Office 2013 Version of software from the Office 365 portal.
This message has been posted on Admin portals in Office 365 since Friday 27th January (although I only just noticed it in mine today as I was having a well earned couple of days away!) but you can read the full support article here:- (Support for the 2013 versions of Office 365 ProPlus ends February 28, 2017)
Of course this doesn’t mean that this version of the software is no longer supported (extended support for Security patches and hotfixes remains until April 11, 2023), but it does highlight the fact that mainstream support for Office 2013 is only available until April 10, 2018. This coupled with the statement in that support article that reads “Microsoft will not provide notification before implementing potentially disruptive changes that may result in a service interruption for users of the 2013 versions of Office 365 client applications.” should ensure that you and your clients begin the process to migrate to using Office 2016 if you’re firmly embedded into Office 365.
This does lend some interesting questions as to where this leaves support for Infopath 2013. Microsoft have been very clear that this will remain supported technology in SharePoint 2016, but have been very careful not to announce any similar information with regards to SharePoint Online, citing the 1 years notice period for breaking changes to that environment. Whilst the InfoPath product isn’t part of the Office 2013 packages that are being dropped out of Office 365 support this does suggest that this could happen sooner rather than later.