1. Walt Commits Suicide
Ever since the flash-forward in "Blood Money," we've all been wondering, "Who is that ricin for?" A large percentage of the comments left by the Facebook community suggests that Walt is going to use the ricin to end his own life. Walt is too proud to take the easy way out. Walt's pride has been through the roof for awhile, but it became obvious back in season four when he basically explained to Hank why Gale wasn't Heisenberg. Remember in the most recent episode, "Rabid Dog," when Walt and Walt Jr. are out by the pool and Walt states he's come too far to be stopped by a "silly little thing like lung cancer," if lung cancer isn't going to stop him, nothing is, if he can do anything about it. He's worked too hard and lost too much to go down easy, and suicide is the easiest ending there is. Additionally, if Walt really was going to kill himself, why would he waste his time by going back for the ricin? He's explained time after time that ricin takes hours to claim its victim, and if you're going to kill yourself you're going to do it quickly. That ricin is for someone, but not for Walter Hartwell White. Lastly, Walt taking his own life would be almost as much of a cop-out as if they ended the series with Walt waking up realizing this was all just a terrible dream. That's all there is to it. It would be an unacceptable ending to a series as important as Breaking Bad. Like I said, whatever Vince Gilligan and the BB writer's room has already done, it's much better than anything we can speculate. Rather than trying to predict how it's going to play out, we should just sit back and enjoy it.