IMHO very unlikely, it's changing most of the plane's worth.Here's wondering if the KJ-500/A units will be upgraded to KJ-700 standards by swapping the triangular-array roadome with the dual-array rotodome in the future, plus other associated changes...
Furthermore, rear side arrays may not be standalone, but rather part of the whole. I.e. just changing main rotating dome with their associated backend and probably crew compartment is not enough.
Not like KJ-500 are already worthless.