Stanford looks pretty evil in this picture. I have a few theories of what might happen.
1. Stanford turns evil accepting bills offer to rule the universe along side him and is killed by the other pines.
Proof: Stanford is a fairly new member that could be killed without making everyone to devastated. killing someone thats been around since the beginning would be so sad and he takes care of the kids would they go to their parents? Stanford has also been gone for 30 years so killing him wouldn't matter to anyone other then those pines unless he did turn evil then they would care less. In the trailers everyone looks sad maybe its because of his betrayal.
2. scenario 1 occurs but isn't killed and turns good again but only after Stanley dies saving the kids.
3. Alex said at least one character won't make it out alive I quote "at least" so the mayor died I can probably assume bill dies and Alex also tweeted out something that makes me think it will be a pines i don't have this tweet for evidence at the moment.