Well…for some people, the game isn’t over yet. There are a few groups out there that claim the canon is still a work in process. Their most formidable entry is “A New New Testament”, which incorporates additional gospels, epistles, etc, right alongside the familiar ones, not in an appendix.
More than History Channel conspiracy garbage, they take it a step further, and claim to be adding certain books - voted on by a panel - to the NT canon, now. It isn’t just liberal scholars, but some heavy denominational administrators from the Mainline. In a few years, I think you will see rival panels, which may choose to add - or subtract - different books from the familiar 27. You may have a Bible study with 10 people, and no 2 have exactly the same books in their “New Testament”.
This puts the need, in the 21st century, for the living Magisterium, in a different light.