"We're trying to figure out what we want to do long term with the position we have now," Notch said in regards to Minecraft's absence from Steam and Mojang's continued autonomy. "We only recently decided to stay as independent as possible and cancelled an unannounced project that we were doing in collaboration with someone else. It's going to be an interesting future."
What this unannounced project actually was, or who Mojang was working with to create it, remains to be seen. Maybe it was, like, some kind of witch simulator? Or like, an underwater welding game with gravity control elements and realistic fluid dynamics? Someone should get on those.