Maybe that is where the money came from for the 5 g550's. Not a bad exchange, the G550's are going to be quite capable and that adds significantly more air frames with those types of capabilities, which are/could be complimentary. CAEW and ISR.
I think the G550’s should be seen as part of the EP3C/AP3C replacement. As I understand it, the idea is to get 15 P8A, 7 Tritons and up to 5 G550 to replace the 18 AP3C Fleet.
I’d like to see more airframes in that group. These planes will fly constant missions and tend to get worn out. Getting say 25% extra would allow cycling the fleet through deep maintenance to keep the fleet going longer.