If Navantia are offering that large a missile capacity, it would have to be in a new hull design as the F100 hull is very tight with the current AWD configuration, thus there would be no commonality with the existing fleet.
The sensor design (including CEAFAR 2 radars) is virtually complete for the Hunters and that would carry over to AWD variants based on the Type 26 hull. If a new Navantia hull was selected, all that work would have to be done again - more expense plus taking up a lot of time that we don’t have.