Former Congressman Anthony Weiner posted a thank you message to supporters on Facebook this afternoon that leaves the door open–ever so slightly–to another comeback run. “What’s next? I’ll keep you posted on my plans. But I hope we keep the band together,” he wrote in the message to supporters posted on his Facebook page. “(Who knows, maybe I have a third book of ideas in me!)” he added. Mr. Weiner, who lost his race for mayor this summer following revelations that he’d continued sexting with women long after he resigned from Congress, has kept largely out of the spotlight since...