Secretary of State John Kerry, in one of his final public appearances before stepping down, jokingly suggested Tuesday that the Trump administration may only last a year or two. Some of his audience at the World Economic Forum in Davos — which this year has many attendees absorbed with the looming inauguration of President-elect Donald Trump — appeared to enjoy the comment, laughing and clapping. Referring to the prospect that the Trump administration may walk away from the Iran nuclear deal, Kerry said that doing so would harm American credibility, “and it will hurt for the endurance of a year,...