I had a particular idea of how, if I were the showrunner for G5, I would ultimately conclude it, to not only resolve things there, but include a callback to all that came before.

To help explain and settle why events from G4 take the shape they do to create the semi-dystopian version in G5, the climax of G5 would include a moment of utilizing time travel to neutralize a threat that will destroy the entire world and which cannot be defeated unless smothered in the crib. Taking cues from the likes of Avengers: Endgame, X-Men: Days of Future Past and Spider-Man: No Way Home, the G5 protagonists must travel back in time to not only G4, but all the way back to G1, and change history for the better. Thus, this would also include the likes of Megan as a main figure in this climax, even when standing alongside the various generations of characters fighting to change this particular event and impact Equestria down the line.