Walt's cancer could be back. It showed him getting a CAT scan and then it zooms in on the paper towel dispenser with a huge dent in it. No clue if Walt did it, but it's a good bet if the cancer is back. This also came right after he claimed he was "done."
And just to refresh my memory: That book and quote came from Gale, right? He gave it to Walt when he started teaching him in the lab.
I'm dumb and a fucking simpleton, but I'm impressed with that revelation. You know it has to happen, but the show lulled me into a sense of security. I didn't really think about Hank vs Walt, even though it's such a prominent undercurrent. Hank finds out in such a simple way too. FUCK.
Walt vs Hank was what it ultimately had to come down to. I figured there would be more gang violence involved, and there could be some, especially if Walt is being sincere about being out of the meth game. Someone is obviously going to be pissed that Walt's product is gone. I think Walt's change in appearance in the first scene is because he is trying to dodge the people he made the deal with to replace Mike. We saw the money he made in such a short period of time....have to think the new distributors were making a ton as well. Unless Walt was willing to sell/give them his recipe, you have to think they would have a difficult time just leaving it all on the table.....which is why they sent others to either kill or get the recipe from Walt.
I have some other theories on how Walt vs Hank goes down, but I'll tackle those later.
Going back to Walt's cancer, I'm pretty sure it's back. I went back to review a couple episodes when Jesse was talking about his aunt's cancer, and that fly showed up when he was talking about it. Same with the fly in the last episode. And the dispenser that he punched back in season two. All is symbolic with it being back, in my opinion.
As far as Hank vs Walt goes: I'm conflicted with how it'll go down. A part of me wants to think that he'll help Walt get out because he's his brother-in-law and he's stated repeatedly that he's tired of his job. He'll confront him, they'll discuss everything, Hank will warn him about what's about to happen, and he'll get out.
Another part of me says he's embarrassed that everything happened right under his nose, so he'll trail him for a bit before going in. He'll definitely be conflicted for a while. I'm curious as to how he'll approach him. There's really no evidence, especially if Walt really is out. Everyone is dead except Jesse, Todd and his uncle, Saul and Skyler.