I doubt they would pass any cost savings on to customers, any reduction in manufacturing cost would just go to making the X more profitable per unit for Tesla.
The price point is dictated by positioning in the lineup, an X has a certain price gap between it and the Y, much like the differential between a BMW X3, X5 and X7, the delta in cost of manufacture is probably minimal compared to their respective price gaps.
although the profit margin on the X and S are reputed to be much higher than the 3 and y, by no means are they almost no difference in cost. lower volume usually indicates higher cost in and of itself. Every little bit you add increases the cost. there's a reason things like this cost more, and it's not just because the manufacturer wants to make more money. I don't think people so light in the head they would pay more for nothing!