I regret launching this prematurely last year, and doubly so just kinda forgetting about it after. That was pretty dumb of me. But I stand by the idea that this is tropeable. I disagree with the assessment that it has to be either "the first installment repeats itself in a way that wipes the previous version from continuity" or
"the anniversary references the first installment," when how the homage happens is beside the point. If that's not clear than that needs to be fixed.
If there's anything I regret it's making it so specific to the Book Ends
idea. Loading an anniversary with continuity references in general is a far more prominent trope and one that's not explicitly covered by Milestone Celebration
, a trope which seems to be just "the show acknowledges its hit big numbers in some way."