It seems it has not been widely and properly communicated
As you may know with System Center Configuration Manager (SCCM) you were able to setup an hybrid mobile device management with Intune, meaning you were able to use Intune to register your device and use SCCM to manage them.
So, since August 14th 2018, this hybrid mobile device management is deprecated.
If you are using this hybrid MDM feature, you will still be supported until next year (so probably until August 14th 2019). If you were not using it but were planning to, you may have up to November 2018 to implement it, otherwise you will be block.
This can quite make sense with all the improvements with co-management capabilities added in SCCM current branch.
You can get more details here https://aka.ms/hybrid_notification to move from Hybrid MDM to Intune.