The only thing ever said about 144,000 souls in the books is by the Wracu Akka faces off with. That is the number the population has to be reduced to to shut Eärwa off from the Outside. The No-God's is the Consults tool to do this quicker. Once the No-God rises there are no more births. So, many have speculated as to why the No-God even went to war in the first place. They could have waited until people died off and with no more babies being born it wouldn't have taking very long.
That's good to know, but I think there is more to that number, I'll have to reread that section. If it is the case that the population needs to be 144k in order to shut out the Outside, what happens if one trips and falls to their death? If everyone is sterile, than you can't replace a lost person, and the number is broken. However, if it is the case that the number of souls need only be trapped in the Carapace, as I believe is the case as revealed in Akka's dream of the chain gang being lead into some clanging mechanism, than the Consult need never worry about losing a soul here and there, and they would only have to eliminate all remaining living souls to attain the magic number.
However, that would mean that the Skylvendi would have to be betrayed at some point, once the rest of humanity is eliminated. I wonder how they felt when their wives were rendered barren by the No-God? They seemed to be ok with it, fighting alongside the No-God at Mengedda. I can't wait to see what the battle will be like between Cnaiür and the People, and Proyas and the Ordeal.
Alternatively, if it is the case that the Carapace is not some kind of Wathi doll of epic proportions, a giant soul trap, than there would have to be a population of souled beings kept around, and maybe that role would fall to the Skylvendi, some kind of chosen people? Perhaps the Consult could grant them immortality, keep their population at 144k, and use their Tekne to replace any Skylvendi who die, like in an artificial womb of some sort; I'm sure it would be within their capability.
That also raises another concern though, would the Consult have to hunt down all artifacts that contain a soul, like Wathi dolls, and the masks used by the Nonmen to imprison souls? What about any wights left around, like the Nonman King in Cil Aujas? I guess all will be revealed in The Unholy Consult. Thanks!