Jesse Plemons is in the main credits now instead of just guest starring, so he'll definitely play a big part in the end. He's the one making the shitty quality meth so he'll probably concoct a scheme to force Walt to cook again, with Lydia's help. Maybe holding Holly/Walter Jr for ransom until he teaches them his recipe. Or holding Jesse's family/Andrea and Brock hostage for similar reasons. Walter Jr will die. I'm almost sure of it. At first I thought it would be in a car accident since the show has hinted at his inept driving abilities with the dual pedals before, but now I think Walt will be responsible for it, directly or indirectly. i think this will be the straw to break the camel's back for Walt and he will finally realize the monster he has become. I doubt Skyler will die. Hank either. I also think Walt was getting the ricin to use on himself in the flash forward, as a way to assert control over his cancer and those out to kill him (whoever they will be). It would be a small victory for him and the shows creator has hinted at that.