PS1 - $49 (May 2002)
It's crazy to think that the PS3's RRP was only dropped to a minimum of $269 and recieved no price cut after the PS4. It's no wonder it's legs were so short.
So PS4's legs post-ps5 all depend on if it gets a price cut, and how far down they can go. A $49 console... I had no idea PS1 went that low. xD
Just to add onto this with adjusted for inflation prices:
PS1 - $69
PS2 - $118
PS3 - $300
So the PS3 at it's cheapest RRP is the same as the current RRP of the PS4. Mental. Guess they really never managed to get production costs down that far and that really shows why the PS3 legs were so bad.
We'll never see a console as cheap as the ps2 again though, even adjusted for inflation. The controllers are far more expensive to produce then they were, the now necessary inclusion of storage also drives up the minimum possible price.
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)