In very broad terms we will lose a major ISTAR asset (search, find, fix and in some cases destroy) its capability can not be replaced by any other current asset. The idea that 10 or more Squadrons of FJ is needed in the current force structure is ridiculous and may cause much more harm to our future relevance.
MPA has always been considered the Cinderella of the RAF and the FJ centric hierarchy have never allowed the MR2 to reach it's potential, left unchecked I'm sure they wouldn't be to bothered about the MRA 4 either.
Bring on the SDR, hopefully homeland defence will be top of the list and the politicians might see what an error they have made!
