Is Sierra Returning? For Realsies?

Sierra Entertainment has been laying dormant for years. The developer is best known for its adventure titles in the 1980s like King's Quest, Space Quest, and Leisure Suit Larry. Now Activision is prepared to reveal something special that Sierra is working on at gamescom in Cologne, Germany.

A teaser site at sierra.com has an extremely short trailer (posted above), showing a backpacked, geared-up figure struggling against a snowstorm who has finally reached the bottom of a mountain. As he runs toward the mountain on what's seems to be a frozen lake, the camera pans out revealing the Sierra logo.

I first through this was a re-imagining of Prey 2, but no, that's something from Bethesda and I have no idea what's happened to that. The trailer doesn't seem to be for anything like Crash Bandicoot or Spyro, Maybe's it's SWAT 5? What do you think it might be?