fascinating and believable, could be. There are so many could be's and moving parts in this series though. Without doing much research I was just figuring that Walter had been outed as Heisenburg and the spray paint was a sort of mocking by the local kids, who were skating in the pool. The family was gone and Walter was on his own running from the law or the gang. I couldn't figure out why the house was fenced off though. I like your version better, and agree that the pool probably plays some sort of greater roll, as it has played major roles in the past, anywhere from Sklyer trying to drown in it to Walter sitting by it and pondering whatever. In fact this last episode started at the pool, which was the last time the family (Hank and Marie included) was whole.
I've just decided to vote for anyone and everyone to die and view Walt as the villain. It seems easier to let go of this series like that and vote for a spectacular ending. I think I have figured out their format though. We will see bits and pieces of the ending at the beginning of every episode, starting with the empty house and Walt getting the ricin, but we wont see the final twist till the last episode. Kind of like how the did the second season with the plane crash.