It depends.
I don't know how much a PS4 costs to make. When it came out the reported cost was $381 [about 40,000yen] Source:
https://gamerant.com/ps4-cost-build-manufacture/
But lets say,
just as an example, now that manufacturing costs are down, it costs 15,000yen to make in 2020. And it sells for around 33,000yen. So the profit is 18,000yen per unit.
Now say Sony decides to drop the price of the console to 20,000yen. They will now have a profit of 5,000yen a unit.
I am sure there would be an early uptick in sales but would the system
consistently sell more than 3 times what it sells now to account for the lost revenue?
Or how about a scenario where the PS4 only costs 10,000 to make. At the current price point there is a profit of 23,000yen. A 20,000yen PS4 would bring in 10,000yen profit. Sony would still have to sell 2.3 times as many systems.
Going the other way, let's say the system costs 20,000yen to make. In that case there is a 13,000yen profit per unit now compared to just breaking even.
Again, I pulled those numbers from my butt, but
Sony knows the actual numbers and has done the math and perhaps they decided that it is indeed not going to bring in more money with a price cut or at least not enough money to risk cannibalizing sales of the PS5. Nintendo made the same decision with the WiiU.
If they had done it years ago it might have been in Sonys best interests to take a loss on the consoles to make it back in software. But at this point not much software is moving, there are no real evergreens on the system and 1st party development has mostly moved on.