It'd easily be a $10-12 bn program to replace those Block-15s. If LM doesn't secure it, AVIC will, and right now the White House doesn't want to lose any deals of that size to China. Moreover, pressure is mounting on countries to chill with their big Chinese imports, Pakistan won't be an exception IMO (e.g., IMF, FATF, EXIM loans, FDI, etc and other leverage points). The PAF might be the best positioned to sort of balance the matter.
Just my speculation, but through the rest of this decade and into the next, I think PAF will pursue a mix of J-10CEs and new F-16s, and then add NGFA to the mix as the new spear-tip.