Regarding "evolving IADS", IMHO, as usual the advantage is on the ground systems side (as they are not limited that much in size, power, network links, etc.) Therefore, taking into account very long life cycles of modern planes (as compared e.g. with 50's and 60's) "modifiability" (quick and cost effective) becomes more and more important for any aircraft.
A_Van, whether it is "quick" or "cost effective" isn't as important as being adaptable/modifiable. If it isn't modifiable, no amount of money or time thrown at it may meet the need to adapt.