I have some thoughts about a way they could mix up the format.
In the next season, have a "core" group of traitors, keep the "secret traitor" format, but this time make EVERY remaining player a secret traitor. Let everyone know that there are secret traitors, but don't say how many.
Obviously this will mean that traitors will have to be able to be put up for murder. As for committing the murders, have all the secret traitors vote for one person to be up for murder (out of who they think are faithful) and have the core traitors choose who to murder out of the three (?) who have the highest votes.
Could you imagine the round table discussions if everyone was a traitor? I'm not sure how to end the game though, I think eventually everyone would clock onto the twist. Maybe towards the end the winner could be decided by a jury of the people that have been banished? This could distinguish the murdered from the banished - if you're murdered, you're dead, if you're banished, you're still alive, you can get your revenge.
Thoughts?