Migration from hybrid active directory & hybrid exchange to cloud-only environment

Hello chrisslroth 

Generally, the implementation of a hybrid deployment is subject to organization requirement as it offers flexible benefit of on-boarding and off-boarding mailboxes as required. However, you could move all mailboxes to the cloud and continue to manage users in the cloud, if that fits into your organization future plan, then decommission your exchange server(s). You could decommission some or all of your exchange servers depending on your use cases. You could find typical scenarios and what to do in the useful article.

Useful Article
https://learn.microsoft.com/en-us/exchange/decommission-on-premises-exchange

Please do not hesitate to contact me with related questions.

Thank you.