There's gonna be another scene with Walt, so that would have to be a flashback since he's dead by now.

Jesse is probably a flashback too. This is only a couple months after Jesse ended up in Alaska, and I don't know how either finds the other (without a Robert Forster scene). Somebody guessed that maybe Gene gets caught and turns in Ed Galbraith and he gives up Jesse. But that doesn't make a lot of sense.