I sympathize with the struggle of an ongoing narrative-structured series. You work towards a big culmination (i.e. Avengers: Endgame), but what do you do when you've told a complete story and you're not ready to stop? You invent new struggles and antagonists and hope they're well received. Sometimes a good, complete story that makes its audience long for more is better than churning out new content that underwhelms and potentially tarnishes the legacy of the past.
Yōikoma 139
I remember these guys...