One of the many possibilities of Jacqueline’s future is the eventuality of giving into the corruption and evil powers that have manifested within her for a long time. However therein lies a split of at least three other possibility branches.
Branch A: After finally managing to defeat Aku and kill him, Jacqueline absorbs the leftover, dispersing power of her former father. This leads to her becoming overwhelmed by the power and corruption and giving into the evil side of herself. She then gains control over the world and beyond
Branch B: She finally defeats Aku and absorbs the leftover power, but manages to stave off the corruption. Eventually she returns to the past and kills Aku of that time. However absorbing the essence then leads to her corruption, and so she rules the timeline of the past.
Branch C: Jacqueline is eventually taken over by the corruption in time, and rules alongside her father, Aku.
Regardless of which possibility, Jacqueline differs from Aku in that thanks to having formerly been human, she has more of an understanding of emotion and the mind of people. She understands that one of the best ways to rule over a populace is by also appealing to various aspects of them.
Willing to provide help in exchange for favors that she could collect in time, Jacqueline is willing to help mortals out with some of their problems. She feels that there is more worth to a society that is capable of sustaining itself and growing strong than one constantly ruled chaos and the unknown.
Granted, that isn’t to say she doesn’t have a temper, and many would realize quickly that she wasn’t someone to cross or backstab on a deal. However, Jacqueline is fully content to manipulate and control things from behind the scenes in the shadows, which she thinks is the best way to reach her goal.
Overall, her mentality is that while she can indeed be feared for her power and just what she could do, she could still be respected and looked up to as a being who can provide and help when needed as long as people are able to pony up on their end.
There was an entire episode of him being infected by Aku and slowly turning into another Aku, but Jack managed to revert the transformation from inside.
The episode is called "The Aku Infection".
But geez, I really love what you did with this idea.
Though I think here we have to consider that unlike in that episode, Jacqueline has been dealing with all of this for years. Slowly feeling aspects here and there, and likely eating away at her resistance behind the scenes. Her spirit and everything was and is strong, but at the same time she likely fully collapsed and it took over after a long struggle.
Granted, this doesn't mean that the good in her is gone. It could still be in there, just suppressed and needing a special catalyst to get it to surface back up. It's not impossible for her to be restored and for the corruption to be fought back again.
You could probably look at it as her just being tired and 'resting'. Though I dunno if that works as a whole. The thought itself is neat.
And why you always gotta leave me the hope of bringing a corrupted lady's mind back to her senses? Makes my Hero Syndrome act up.
Now we have seen the future (and it was good). Why not more phases of the in between Jacks transformation, and all the phases of her slow corruption as Aku spoils his greatest enemy into submission.