Windows 10 Offer Expiry & new major update
Microsoft haven't exactly been trumpeting the imminent expiry of the 1 year free upgrade offer over the airwaves, but come 29 July 2016, the offer will expire and you will have to purchase a copy of Windows 10 if you wish to upgrade. Pricing for Windows 10 Professional is around $220 inc GST.
Having said that, it is in your best interest to test Windows 10 with your apps, before committing to an upgrade of all PCs in the office. There could be issues with compatibility, necessitating fixes or upgrades to your software, as part of upgrading Windows 10.
Microsoft have also announced that the next major update to Windows 10 will be released on 2 August 2016, this is only a few days after the expiry of the free upgrade offer. Because of the policy of mandatory installation of updates with Windows 10, you need to ensure that this major update is tested on a couple of PCs before rolling it out. Configure the update policies accordingly to defer the upgrade for a month, in order to give you adequate time to test and prepare.