Not OP, but given the witness selection system's dependance on voting I would assume that, barring a witness' removal of themselves from consideration somehow, they would cease to be a witness whenever they no longer have one of the top number of votes.
But I've never seen this explicitly stated anywhere...
I think you're correct, I just don't think there's a way to actually remove the witness properties of an account once they are set.
Yeah, and upon further thought, I'm not even seeing how someone could remove such witness status from their own account, as I stated earlier might be possible. Perhaps that partially explains the number of Steemit employees, and such, on these listings.
Doesn't seem to be the best way to handle this issue long-term though. I must be missing something...
Which, coincidentally, is part of the reason so many people avoid voting in the first place - to avoid making a poor choice unintentionally. Even if you find some info. to inform your choice here, important particulars are still unable to be found, making the decision process somewhat murky...