I agree with most of what you wrote, including this. Walt can't die at the end. He can destroy everyone around him, but "nothing stops this train". It's the end of the series, so if Walt dies, so does our imaginagation of what happens to Walt after the show is over. Despite Walt's decline into Scarface, I'm still "rooting" for him. I'm also rooting that Hank catches Walt in the end. But just like the Sopranos series finale, VG can't kill off Walt. He might leave it vague (just like Tony Soprano, who I believe was not killed in the series finale), but it won't be certain.