How does this affect me?
Beginning September 30, 2018, users in your organization will only be able to view Visio diagrams in their browser, but not create or edit. Visio Online viewing is available to most Office 365 subscriptions.
What do I need to do to prepare for this change?
iFrame with Visio Online APIs instead of Visio Web Part with Visio Services JS APIs
I will be preparing a part 2 of this blog post on how to implement the above stay tuned.