Even if what you said was a supposition, this is fantasy/dreamer economic based on no other facts than what you think will happen. What's even more amazing is how you seem to completely ignore the fact that reducing the total gil and NPC prices will also make it harder for everyone, and even harder for new players, to make gil than it is now in your theory. In the end the psychological effect of seeing a lower number will be quickly chased away by the frustration of having a hard time making gil and the inflation that will happen. Be it player driven inflation or, for a worst case scenario, RMT driven inflation. Again, stop dreaming and don't underestimate human stupidity.