The teaser talks about a beginning and the main focus of Jolla was to bring SailfishOS to other manufacturers. Therefore I think that the announcement is about a new device (and partnership) with other manufacturer. I think that it has a lot to do with the sale coupons Jolla has been offering last few weeks. They are clearing the shelf, because other manufacturers are likely to have a better price point. Judging by the teased design, I would say the partner might be Xiaomi, but it might be just a wishful thinking