Don't be surprised if Boeing announces a 787 at the last minute. But above all, it's already been virtually constructed and many real parts are ready to be fitted together.
Just a thought.
Remember Boeing was ready for a all new 4 engined
airplane, albeit that engine wasn't available at that time,
nor was the market, before they opted for the twin we now know as tripple 7.
Not saying that Airbus is incapable or something. Both manufacturers offer excellent products.