Unmarked spoilers ahead!
The Audience was first revealed in the original set of 4 teasers. The other teasers revealing Ms Undertaker, The Banker, and the Bandit. All three of them are not villains. While this is far from conclusive, it seems weird to have three normal good puppets and suddenly main villain.
However, what basically confirms this in my mind is that if the Audience is some sort of cult dedicated to Showdown Bandit, and we PLAY as Showdown Bandit, it would be very weird for them to be antagonistic to us
What I think will happen, is that the Audience will be a sort of Neutral figure in the story. Not necessarily good or evil. Just a creepy cult that just can't move on from the fact Showdown Bandit was cancelled.
- That's assuming that there won't be events that cause the Audience to become antagonistic to us, like a rebellion from the puppets. They're likely not the Big Bad (that belongs to the puppeteer) but that doesn't mean they're won't possibly be threats in the future.
- That's a fair point.
Him starting to speak could also be a part of the Gameplay and Story Integration, maybe some sort of sign that he's becoming more independent from the Puppeteer (the player) and slowly grows into his own person?