Walt will wind up being killed by his own ricin or something. It will be the "symbol" of his "self-destruction". Making that ricin marks the point at which he was no longer cooking a little bit of meth just for the money for his treatment, making that ricin marks the point at which Walt accepted this as his new life. Even after killing that dude in the basement, walt still could have walked away.
His commentary with (Walt / Skylar) / (Hank / Cleptopatra) is really very, very shallow and ultimately just cheap. And maybe that's even his point. A lot of the talk surrouding these sorts of issues is shallow and cheap.
But that's why Jesse saves the show. There is some substance to Jesse.
That's why Gus was a great adversary, he had that depth that Jesse has. That's why Saul and Mike were such great support characters. They're both utterly one dimensional and they fully embrace it. It's really bizzare, his main characters are his weakest characters.
Cranston is a good enough actor to pull it off. Skylar, Hank, and Marie really just aren't. A lot of that is the lines they're given.