In the past ten to fifteen years, P-3 Mission areas have expanded considerably in terms of the varieties of kit and sensor packages used on patrol flights, to include some "feet dry" missions.
P-8 will fit into a joint mission requirements niche that isn't solely "maritime" when all is said and done.
As to "lookouts" there are a variety of sensors now in use that are far better than Mk 1 Mod 0 eyeball.
I am still not sure if standard P-8 kit will include a refueling boom. I think it should, to fulfill maritime patrol requirements.
Been a few years since I was in a position where I knew a bit about this program, so I don't know what changes have been made.