I once pondered something similar, of what would have happened had Sailor V decided to "choose love" over duty in the final chapter of Sailor V and went with Danburite.
Artemis would have yelled at her and tried to talk sense into her, but if that failed he would have been forced to flee and locate/awaken the rest of the Senshi in order to stand a chance later on.
- The Mysterious Traveller wrote:
the Crown Arcade serves as the main hub of their operation...are there prison cells or maybe even stasis tubes down there that could be used to contain one or more of the gals if ever she turns against the rest?
I doubt it, I can't see the cats planning that far ahead. Though in the event of a senshi going rogue I'm sure they could conjure up a stasis tube to hold her in since Artemis was shown capable of spawning an arcade cabinet.
As far as a Senshi falling too far into the darkness to be brought back to normal, I can't see that happening either. Every time a good character such as the Senshi or Tuxedo Mask has been turned evil in Sailor Moon, they've always found
some way of bringing them back to their senses no matter how strong the brainwashing.