In many ways the Neptune airframe is very well suited to the firebombing mission.
It is heavily built with a big wing and good low speed characteristics and excellent visibility from the cockpit. Its Achilles heel is the temperamental R 3350 engines. They don't really have enough power now that purple gas is long gone and these engines are getting harder and harder to maintain.
What is needed is a program to refurbish the airframe and then fit 4000 hp Alison 501 Turbo prop engines. Now that would be kick butt tanker.
Instead everyone seems all hot to tank BAE 146's an program to me that just makes no sense.