Originally Posted by Relentless

Loved when uncle jack starts saying Walt can't kill him or he'll lose the rest of the 80M forever and Walt doesn't even let him finish the sentence before blowing his brains out. Walt was finally beyond greed, beyond money, beyond worldly concerns. The same cancer that had trapped him originally is what set him free in the end. Finally ready to rest in peace, as that last ascending camera shot of his face showed. The exact opposite of the frantic death Lydia earned, laying in bed with her humidifier going full blast and finding out it isn't just a head cold.

Brilliant writing...

Originally Posted by akkad47

Writing this before I read all the other theories here:

- The Ricin is for Lydia to sneak in her Tea. Walt originally wanted to turn himself in after calling the Feds from the Tavern's booth. Watching the Report where he sees Elliot and Gretchen discredit him after it's mentioned the Blue Meth is still in Circulation in both the South West and Europe is what triggers him to return home instead. Killing Lydia makes sure the distribution of the Blue Meth dies.

- The Machine Gun is obviously for Jack and his Nazi Crew, maybe even for Jesse so that the Blue Meth dies once and for all production wise