We’re delighted to announce that Microsoft Hybrid Agent has reached General Availability! We first talked about this agent nearly two years ago at Ignite and we’re very happy to have reached this imp...
Updated Jul 01, 2019
Version 2.0
Blog Post
Answering my own question : Switching modes from Classic to Modern It is possible to switch to Modern Hybrid (Hybrid Agent) after successfully configuring Classic Hybrid (publishing EWS namespace + allowing inbound), but we only recommend doing this if you are blocked migrating to O365 after this setup is complete. If you are successfully migrating mailboxes your users are experiencing hybrid features and chose to revert to Modern Hybrid, see the previous Constraints section because not all hybrid features or experiences are supported with the Hybrid Agent. If you have weighed the pros and cons of switching from Classic to Modern and choose to proceed, you can do this by deleting your existing migration batches and migration endpoint and re-running the Hybrid Configuration wizard and selecting Modern Hybrid. -- in https://docs.microsoft.com/en-us/exchange/hybrid-deployment/hybrid-agent