The other problem, and I went and gave an impassioned speech on the Twitch Dev Forums is, once they are marked as a follower, a follower they will always be. Twitch is not going to ever provide a way to easily determine if a person doesn’t follow, in the words of their staff – it makes it easy to abuse people that unfollow. So, if you are fine with someone following for those permissions, then just unfollowing and keeping them, that will work.
When I mentioned the idea of rewards based on followers, a regular contributor and author of a large bot, suggested that it wasn’t the best way to go as well for the same reason that Twitch staff gave.
So, the bottom line is - this won’t ever be added to the bot by the core development team, because there isn’t an easy way to see if they stopped following, and, all they would have to do is follow/unfollow/follow/unfollow for the perks. Of course, the bot is open source, so the feature could be added if desired to your build.