they could've reached over 90m PS3s easily with a cut to $200 in September 2012 (for the 160gb)
They should not miss their chance to get more hardware and therefore more PSN accounts and software sales before PS4 runs out of life. Gotta get it to the mass market price PS3 never reached. There's no cell to keep it expensive this time. They will still profit at $200 and it will get them huge sales. Bundle it with a big software title like GoW, Spidey, Days Gone, etc.
If they don't lower price on both it will be a weird situation of PS4 Pro being the same price as PS5 and PS4 base being just $100 cheaper. Would kill late sales of PS4 (that's one of the big reasons PS3 got cut off was because its price was still too high).
In the U.S., the PS3's drop in August 2011 from $300 to $250 has almost no impact on sales. There was a roughly 20% YoY jump in September, but that's about it. August was still down, October was flat, the holidays were barely up (and that could be due to Black Friday deals, which first started to be a big deal for hardware that year), Q1 was down YoY in 2012, and Q2-Q4 were down even more. In Japan, there was a ¥5000 price cut at the same time, and the impact was likewise very modest and quite short-lived.
Late-life price cuts like that don't do anything major. There is absolutely no precedent for modest price cuts providing a major stimulus to sales after the first several years (price cuts generally result in diminishing returns over time), nor for deeper price cuts being issued at all this late in a system's life. At best, it may reduce the rate of decline a bit, but that's it. Sony is going to look at that experience with the PS3 and likely come to the conclusion that the PS4 isn't going to see any significant growth anymore even if they issue a price cut.