Until Dawn was a real sleeper hit for Sony. The game wasn't expected to do great, but actually came in to really impressive reviews and sales when all was said and done.
However, that doesn't seem to have prompted any rush for a sequel. Supermassive said in an interview with Gamesindustry that while the developer is working on something, it isn't 2. Managing director Pete Samuels said:
There's a lot of speculation about what we're doing and what we're working on right now. We're not working on Until Dawn 2 at the moment. We're working on other things.
I'm actually a little surprised by that. I think there is great potential in Until Dawn 2, but Supermassive are a talented studio. I'll be on board for what ever they are in fact working on.