From my reconnaissance today:
GA540 is not signed in Macon anywhere west of the US23/80 split east of town.
GA88 has been truncated, though I can't say for sure exactly how far. It is definitely not signed anywhere west of GA171 (where I turned off). GDOT's state map seems to imply that it now ends somewhere in Wrens, though I don't know if it's at GA80_E or US1/221_N or somewhere else (the county map is no help, as it's out of date and still showing what's now GA540 as GA88).
However, unlike GA88, GA57 is still signed along GA540, so no changes necessary there.
I did not see any signs at all for GA243, so I believe that route has been fully eliminated in favor of GA540.