For decades, the Gulf superhubs of Dubai, Doha and Abu Dhabi performed an improbable trick. They redirected millions of people travelling between the West and Asia to connect through their airports. Last year, the three airports handled about 182 million passengers, three times the traffic at Hong Kong airport. Dubai alone handled 95.2 million, the highest ever recorded by an airport. The Gulf’s hub-and-spoke model – funnelling passengers through a central airport to multiple destinations –...