I'm currently in the dangerous state of motivated, but not inspired right now.
But I've had a couple of ideas, since I feel like mangling the Magical Girl genre for some reason.
1) What if Crystal Tokyo wasn't the utopian city-state people think. No, it's not evil, but it's more like the Old Republic from Star Wars.
Generally speaking, things are pretty good for the masses, however since this empire is so large, the Senshi can't put out every fire and generally only go after the big fish.
If you'll pardon the mixed metaphor.
And what if the most wanted fish in this lake was none other than
Cobra?
Cobra's busy recovering his memories of his former life while dodging the fuzz and maybe seducing one or two of his pursuers.
2) What if Setsuna decided that Usagi is a terrible choice of monarch/ruler and feels that it would be better/suitable reward if she was in charge?
Not necessarily Evil!Pluto, just one that feels that she could do a better job.
3) What if there was a new magical girl on the block? One that dressed even more scandalously than the Senshi and whose source of powers was unusual?
Yes,
The Domesticator is in town and ready to clean up the filth of the Negaverse.
Comment as you see fit people.