If Airbus, Kawasaki, Alenia, and Lockheed can't do it in three years, then what is so special about Boeing that they can?
First, I think it's generally agreed that for many reasons, including Seedcorn and a long history of operating U.S. aircraft, the P-8A is the only type that the UK would ever select without a competition.
Second, Boeing has a hot production line and the USN has a substantial inventory and backlog. This opens up many options (such as leasing aircraft initially).
However, the tenor of discussions at DSEi this week suggests that nothing (at least nothing permanent) is going to happen soon.