They didn't sideline Sansa. Think about it. Jon's priority, as noted, is the WW. He's taking his people North next season probably. But the Wall's never going to have the supplies for them, not when they've only ever had roughly 1000 Night's watch spread between three keeps, nevermind their losses. What show do you think Sansa's going to run? Sansa's likely running the North while Jon's running the War.