Redwood features having Opt-In expiration

Summary:

The link below mentions certain Redwood features that are either already available or will be released in the 25A update, along with their expiration release. What happens after the opt-in expiration release passes? Will both the new Redwood pages/templates and classic templates coexist, or will the classic templates become obsolete?

For example, the feature "Redwood: Use Redwood Style in Movement Request Approvals Notification", introduced in 25A, will become the default setup starting from 25C. What will happen to the classic notification page after 25C? Will both the classic and Redwood versions coexist, or will only the Redwood version be available?