UR 3 for System Center 2016 have started to surface now and in the windows Catalog I have found VMM and SCOM 2016 UR3 packages. There are quite a few fixes and if you have a dev or stage environment you should start to evaluate this new rollup!

SCSM 2016 UR3 could be found in the download center at this link

https://support.microsoft.com/en-in/help/4014528/update-rollup-3-for-system-center-2016-virtual-machine-manager 

https://support.microsoft.com/en-in/help/4016126/update-rollup-3-for-system-center-2016-operations-manager

https://support.microsoft.com/en-in/help/4019979/update-rollup-3-for-system-center-2016-service-manager

There are no UR3 for DPM,Orch, SMA and SPF as according to this page: https://support.microsoft.com/en-ph/help/4020906/update-rollup-3-for-system-center-2016