My general thoughts after BB ended were "He's out, he's gonna find the vacuum cleaner and then disappear to Alaska", as he wanted to do..... but damn, I forgot about the money issue.
Also not only symbolically, but also practically, Walter's Blue Meth died with him, so it would be unjust if it would live on through Jesse. We'll see, I'm sure that if they bother to make a movie about it, the story will be worth it.
Another approach, as weird as it might be, could be making just a Breaking Bad movie for the sheer hell of it, original cast and all, and treat it as an alternate universe story when you have Walt cooking meth and see it just as a one-off approach, like "this is a story that could have happened". It might be lame, I know, but better than those very convoluted situations when you come up with absurd explanations to justify a dead character's return.
To make an example: I have never seen The Sopranos. All I know about this series is that it's about a crime family, and that the protagonist goes to therapy. Also, the finale was controversial or shocking or whatever. It would be such a terrible idea to use the cast to make a standalone story, 2 hours movie about a mafia boss that goes to therapy rather than going into a sequel of the series where you have to justify the absence of everyone who's died or, even worse, pretend that someone who died, surprise, survived?