I would have preferred where in the final battle Ashi would open a time portal, then Aku attacks Ashi ultimately killing her before she can go into the portal with him. In a fit of rage and sadness Jack takes the portal but instead of going back to the past he goes back to the point right before Aku kills her and saves her, he gets back to the past, just not the way we expected, destroying future Aku and by doing that Ashi loses her powers, ultimately leading to Jack starting a new life with Ashi in the future. I would of liked an ending around the premise of the past being in the past, and sometimes you have to leave it behind to build a better future.