2167 is a possible future for humanity in which a Norwegian scientist creates the race of Observers . It was the final destination in Walter's Plan. Walter intended to take Michael to the scientists, who would then realize that they did not need to sacrifice human emotion for higher intelligence. The plan was a success, as it culminated in a final reset of the timeline.
In Relationship to Timelines
2167 doesn't fit on any timeline because it hasn't physically happened yet. It would be improper to label it on the Original Timeline because that timeline ends with the world ending around 2026. This future would never be able to unfold, which is the reason why Observers believed the creation of an Alternate Timeline was needed.
2167 can not be labeled on the Alternate Timeline either, however, because it existed before the creation of the Alternate Timeline. 2167 can best be described as one of countless possible futures, but it would not get placed on the timeline until the timeline has reached that point. Instead, 2167 is existing, presumably simultaneously with other futures, until a definitive future comes to pass.