It seems obvious that Boeing have been panicked into action to prevent Airbus from gaining the total order.
According to a leading aviation magazine, the Boeings CEO talked at the Paris Airshow about an all-new aircraft with new technology which already exists, as a replacement for the B737 which could enter service by 2019. He also said they would make the right decision at the right time.
The chairman of leasing company ALC also unofficially dubbed the new aircraft as the B797.