Insiders worry Pompeo will turn the State Department into an annex of the C.I.A. The greater fear, however, is what happens when Trump tires of him, too. “It’s one thing to sit in on the P.D.B.,” says a former foreign-service officer. “It’s another to have to go out in front of world leaders, and try to explain comments like ‘shitholes’ and tariffs and ‘Little Rocket Man.’”