«لَمْ يَبْقَ مَنْ يُنَقِّحُ الْإِنْشَاءَ»
They agreed that no one remains who can refine composition, and no worthy successor has appeared.
Lam yabqa contains the negative particle lam followed by a jussive present verb, giving a past-negative meaning. Khalaf is a successor or one who follows an earlier generation.
The verdict is sweeping: not merely that some modern prose is inferior, but that outstanding ability has disappeared. This broad claim sets up the counterargument of a speaker who believes the audience is overlooking talent in its own age.