Walter White (through various plot devices) kills the BA dudes, recovers his money, escapes law enforcement, leaves the country, and is free. While walking up the steps to his hotel room a now-grey Anton Chigurh appears behind him with a silenced shotgun.
“Hello Walter”
Cut.
I’d like to change my answer. Walter White, after realizing that he only hurts the ones he loves, decides to leave everything and become a lumberjack.
Walt comes up with a plan to finally get the money to his family. The last step is killing the NAZIs. He barely succeeds, and he’s about to escape, when he comes around the corner and there’s Jesse. There’s a long pan of Walt’s face, as he decides, in the end, that he can’t do it. Jesse turns, and kills him.
Saul Goodman has plastic surgery, starts working out and changes his name to Jeff Winger. Fade to black as he pulls into the parking lot of Greendale Community College.
Walking Bad?
Best theory out there, besides the Scarface one, “Everyone dies.”
Walt goes out firing the M60 just like Scarface. As he lies there dying, Jesse comes up to him and puts his face near Walt’s mouth. Walt’s final gasping words are, “The first person to make the Malcolm in the Middle joke was funny, the 10,000 tools who followed are lame jackasses!”
Maybe the final, final scene, after everything in the finale plays out, the camera lifts above Walt’s dead body and fades to black with the Vince Gilligan credit…
we end it with a little coda scene:
Walt’s back in his classroom, “…and whenever our hero needed a way out of a tight situation, in all of the examples I’ve given, he relied on his knowledge of science. Knowledge, I might add, that was learned in a classroom much like this one. So does that answer your question, Chad, about why we need to learn chemistry?”
The camera turns from Walt back to his bored, spaced out classroom, none of the students paying attention.
Walt mutters under his breath, “is it any wonder we never beat the Czechs in meth purity?”