So as soon as I saw the numbers (i play with subtitles on) at the end of the last mission I knew they were latitude/longitude markers and looked them up. They just point to someplace in NY state. I just came across this article about how it could possibly link the next game (or the one they are announcing in May) to a battle in the American Revolution.
American revolution has been the time period I have been hoping for since playing the second game and seeing where it was going, so I hope this could be true. Not sure about the architecture of the time period and how many large cities or high landmarks there are to climb, but the story would be great. So much history on the templars/free masons and the founding of the US.