Thanks to feedback from event organizers, we recently validated the proposed logic in the Event Info by Stage document. The next step is to implement it.
Proposed resolution
Create the workflow
Capture additional dates so we know when an event should open for sessions, and publish the schedule
Create a view and ECA model to automatically transition to the appropriate state on the specified date
Create a view mode to display key dates, along with a view block to display them on an event
Open an Event Horizon issue to place the block and have it visible during the appropriate states
Implement Smart Menu Links to display navigation to the views pages during the appropriate stages
Open an Event Horizon issue to place blocks and have them show during the appropriate stages
Make a child issue to manage and display CTAs during the appropriate stages