Eh... I don't think so really.
Depends on their objective. A PS5 sale is more valuable to them than a PS4 sale, because the PS5 owner will probably generate more revenue for them in the long run. Selling more systems isn't necessarily their goal. And even at 200/250 I don't see the PS4 being a very attractive proposition because of the 300 dollar XBox Series S and Swtich.
The PS2 had a lot of success post PS3 but that was a different market, and Sony was launching the PS3 at a very high price to the point where a cheap PS2 wasn't going to influence it. I can see Sony just letting hardware sales drop quickly.
well but with 99% of PS4 games working on PS5 and PS+ being a thing it could be worth it to provide an ultra cheap option that's in impulse buy territory to get people locked into their ecosystem. Even if it only results in PS5 sales years later it's still worth it for them. Those cheap buyers are then more likely to get a PS5 when it is cheaper.
I am Iron Man