I don't think there's any way the Braves let either Wandy or Stults opt out. They'll either make the 25 man roster or be traded. Wandy is a better pitcher, so he's probably the only one with a chance of bringing legit value in a trade.
Just spitballing here . . . the Red Sox have depth concerns at SP now that Joe Kelly is hurt and they have a glut of OF. Would they consider a deal built around Wandy for Daniel Nava? Here's Nava's career slash line vs RHP: 293 / 385 / 428.
That example is probably on the unrealistic side, but I think that's the type of deal the Braves would be looking for.