When they first showed Jack's crew at the motel going over the jail hits, I had a strong suspicion that Walt was going after them. I had no idea why, but I just felt he was.The writers room of "Breaking Bad" would insert what they call narrative hooks. Basically references to things or people they could add onto later on.
They actually wrote two entire seasons like that. Season 2, they had no idea what the teddy bear was for. Vince Gilligan just said "a pink teddy bear floating in a pool" and they went from there.
Same thing with the machine gun from season 5A. They had no idea what it would be used for when they first showed it.
There's dozens of smaller examples in the series though, like Nacho and Lalo.
Fred.
I did assume that Walt's entire family was dead though.