Lockheed-Martin is involved with a number of technological activities besides the UK's C130's.
The Airbus A319 airframe is superior to the Boeing 737.
But that is really not the issue.
A jet cannot compete with a turboprop at low levels.
If time wasn't needed at below 24,000 feet. The jet is better.
An MPA will most likely need long periods at low levels. This is where the turboprop wins.
There are too many question marks hanging over the P8.
Horses for courses.
As an aside. The block times of the KLM Electras on the Heathrow - Amsterdam route were only a few minutes more than the jet.
A friend in Varig told me that the reliability of the Electra's on the Rio Galeao - Sao Paulo route was phenomenal. Varig does not exist now but they switched to B737s. Not so efficient.
My point being, an MPA must be a turboprop.
Short term solution ? Invite the French to base a few Atlantique Mk 2's in the UK.