Never, when the ps5 launches and sony drops the price of ps4 slim, and ps4 games start getting really cheap second hand the ps4 will keep selling, will most likely hit 120 million by the end of this year, and 150 million in 3 years.
The problem with Nintendo is they wont drop the price, on top of that games keep their price too high so there's not much incentive to buy it, specially when the new consoles arrive this year the graphics will be way better than on switch, the difference will be too massive for people to invest such money on a weak switch. Nintendo might make a switch 2, but that means the newer games wouldn't run on the older switch, so if they make a new switch, I doubt the current one would hit 120 million.
If Nintendo wants to catch up to ps4, they need to drop the price of the switch, and specially the price of games, this is the main reason I still prefer my WiiU over the switch, because games on wiiU can be bought at one quarter of the price, sometimes less, games like Mario kart 8, new super Mario U, pikmin 3, wonderful 101, bayonetta all cost me around 10 dollars each. Even breath of the wild cost me 20 dollars, I could pay 60 for the switch but why? Its basically the same game, just resolution is slightly better on switch but not worth 3x the price.
This is key for the ps4 success, games can be bought second hand between 5dollars and 20 dollars, even top exclusives, that's what I paid for spiderman and god of war. And ps store always has sales going on.
People said the same thing three years ago, that Switch would be too weak to sell alongside PS4 Pro and Xbox One X. By this logic, the DS shouldn't have been able to sell alongside PS3 or 360 either.
Bet with Liquidlaser: I say PS5 and Xbox Series will sell more than 56 million combined by the end of 2023.