If you use Office 365…. and a perpetual (rather than subscription based) licence, Microsoft has announced some coming changes with the "supported version" of MS Office. 

Firstly if you don't use Office 365 for mail or SharePoint/OneDrive professional this does not affect you. 

MS has made this statement:
Effective October 13th, 2020, Office 365 will only allow Office client connectivity from subscription clients (Office 365 ProPlus) or Office perpetual clients within mainstream support to connect to Office 365 services. (Please refer to the Microsoft support lifecycle site for Office mainstream support dates.) https://techcommunity.microsoft.com/t5/Office-365-Blog/Office-365-system-requirements-changes-for-Office-client/ba-p/62327 

What this means is that from 2020 onward you will need either a subscription based version of MS office (Office 365) to be able to use it with "cloud based services" or you will need to update (and keep updated) your current version of MS office perpetual licence as the Office 2016 "mainstream support" ends on October 13th, 2020. All previous versions will be in the same situation at this point also. 

If you don't upgrade your $265 MS office home and business perpetual licence from Harvey Norman or Officeworks, you won't be able to connect to office 365. As you are probably aware the MS Office 365 subscription version is continually updated and you are always provided the latest version as part of your subscription. 

For business, the Office subscription is currently $10.50 per month extra for Office 365 (A total of $17.50 per user per month vs. $7.00 per user per month for just mail) https://products.office.com/en-au/compare-all-microsoft-office-products?tab=2 Over a 3 year period your MS office costs you $360 but you have the benefit of installing it for you to use on 5 different devices, for example your desktop PC, your laptop, your tablet and your phone. What you are not licenced to do is install it on another PC for another user to use, the 5 licences are for the single user account. 

In the past you have been able to effectively half the cost of MS office for your organisation by purchasing and then skipping the next version. For example purchase 2010 and (when there is a need) purchase 2016 (skipping 2013). However this appears not to be a viable option any longer and you will be required to update each version anyway which makes the subscription model better value. 

I would expect that there is a new version of Office to be released in 2018 based on the normal 3 year cycle from the last MS office release date which was September 2015. 2020 seems like a long way off but you need to be aware to be able to plan for moving to the subscription based version of MS office, knowing that you would be required to upgrade your MS office perpetual version anyway. 

This probably means any new users/PC should go on the subscription model from now onward.