The one you obviously don't live in.
Nintendo did not lose to the Playstation. That only happens in your fantasy.
Nintendo always lost to its own mistakes. What proves it: The WiiU vs the Wii. The N64 vs the SNES. The Gamecube vs the SNES.
Now look, the switch is a console (and a handheld, you know like light is matter and energy?), and it is kicking the Playstation's ass.
The PS4 is still going to sell 120-130 million units most likely, the Switch won't match that.
The fact is
PS1 (100 million units) vs. N64 (33 million units)
PS2 (150 million units) vs. GameCube (22 million units)
PS3 (85 million units) vs. Wii (100 million units)
PS4 (120-130 mill projected LTD) vs. Wii U (14 million units)
Now if I kick your ass in basketball 3/4 times like this you can make all the excuses about why you got beat and how it was your own fault, but no one watching is really going to buy that you didn't get your ass whupped.
Strict home console market, Nintendo does not fare well against Sony. They need the consolidation of their portable market to be competitive, plain and simple.
Unless Sony screws up with PS5 somehow, it'll be more of the same, PS5 will sell 100+ million units, and then MS somewhere well below that. There isn't room for a third home-only console.