Boeing has a problem with its airplane product lineup, and its name is the Airbus A321neo. The A321neo is bigger and longer-range than the Boeing 737 MAX 9. As a single-aisle jet, it’s a different plane from Boeing’s next size up, the wide-bodied 787. Airlines around the world are rushing to order the A321neo, which has posted more than 1,200 orders so far. And that leaves Boeing with a question: Does it need a new plane?