To my layman's ears, some of the conclusions in the cited Lancet article sound chilling, e.g. "...given the substantial volume of case importation from Wuhan, local epidemics are probably already growing exponentially in multiple major Chinese cities. Given that Beijing, Shanghai, Guangzhou, and Shenzhen together accounted for more than 50% of all outbound international air travel in mainland China, other countries would likely be at risk of experiencing 2019-nCoV epidemics during the first half of 2020."

Any comments on the soundness of the methodology used?