The major change we need to recognize going forward is that Microsoft is moving to an evergreen, constant change platform. Updates are provided quickly and arguably at a value by doing it silently (or without a huge annuncement and update bundles). Office 365 gives you the latest updates and features as early as possible so you can continue doing your job productively. For Office 365 services, updates are run in the background as soon as they become available, instead of bundled updates scheduled months apart.
The one problem this causes is that IT departments cannot hold on changes while they test, document, train or even focus on another project. IT needs to focus often on changes and prepare users constantly.
The Office 365 Roadmap provides some value with upcoming changes of features and services on the roadmap in one of several stages: in development, rolling out, and launched.
The Message Center is probably the best management like enhancements I have seen in a while. The posts are related directly with you tenant and provide a summary of what’s changing, how it may affect users, and additional links to help you prepare your tenant. You can also designate what each of your admins within your team are seeing, etc.
Major updates are posted at least 30 days prior to public release, and are moved to the top of the list.
Targeted Release is an early release ring for select users within a tenant who will receive certain changes prior to the rest of their organization. This can be valuable for testing. You must be a global admin to set yourself and other users to Targeted release. If you choose not to opt into Targeted release, you will receive updates when they are release broadly in Standard release.
— Read Managing Changes in Office 365: An Overview of Resources, posted by Jee Soo Hanm 08/08/2018 from Microsoft.