Hopefully, this is just a reminder and customers won’t be blind-sided by the news.
On September 1, 2019, the hybrid capability of Mobile Device Management in Intune will be retired.
The original announcement for this was posted in 2018: Move from Hybrid Mobile Device Management to Intune on Azure
From an email that went out to Intune customers recently:
Microsoft will support hybrid MDM usage only up until September 1, 2019. We will continue to release major bug fixes but will not invest in new features for hybrid MDM. After September 1, any remaining hybrid managed MDM devices will no longer receive policy, apps, or security updates. There are no changes to licensing. Intune licenses are included with hybrid MDM.
Note: This change does not affect on-premises System Center Configuration Manager (ConfigMgr) or co-management for Windows 10 devices. If you are unsure whether you are using hybrid MDM, go to the Administration workspace of the ConfigMgr console, expand Cloud Services, and click Microsoft Intune Subscriptions. If you have a Microsoft Intune subscription setup, your tenant is configured for hybrid MDM.