ricin is for lydia (my guess, because they've been hammering the shit about stevia)
i think eliot and gretchen are safe. i'm thinking their words were just the catalyst to motivate walt to come out of hiding. especially eliot's marginalization of hank's contributions (without which there would have been no gray matter technologies)
the charlie rose interview was the vehicle that allows walt to deduce that:
jesse is alive, and that the nazis did not keep their word to kill him
the blue is in europe, so lydia is still distributing through madrigal
the blue is in the southwest, so the nazis are still distributing domestically.
but they better spend a few good minutes of the finale explaining how a weak, sickly man was able to outrun the sheriff. did he use the $100K to buy the bartender's vehicle?
how would walt escape a chris dorner type dragnet in such a remote location?