> it will be more than a decade before Comac will have the manufacturing capacity to fill even domestic orders

If you think that a decade is enough time for Boeing (or Airbus) to react to losing one large market and having a new competitor encroach on existing markets, then I suggest looking at past airliner development programs.

A decade is nothing in this industry. And China, specifically, is known for being able to scale manufacturing - so they may not have a decade like us Westerners think.