That era is not over. My kids and their friends and us parents play a lot of couch Nintendo games on the Switch. Mario Kart, Mario Party, Overcooked, Lego Party, Super Smash Bros. There's a multiplayer mode in Super Mario World 3D and Super Mario: Wonder.
It's only two player but my older son and I are working on Lego Voyagers. I'd like to play It Takes Two and Split Fiction with my spouse.
I do like the idea of the asymmetric multiplayer games but I am not aware of any that work with the Switch. They might be out there though.
It may not be completely over, but it’s far from the focus of multiplayer gaming.
Many games that used to offer couch multiplayer (e.g. split screen) options no longer do.
The upcoming Starfox remake is a great example (no split-screen multiplayer options, where the original did).
I can’t remember the last time I’ve seen a 4-player split-screen FPS (like Goldeneye 007).
Can you find games that offer couch multiplayer? Sure. But it’s not something that is a priority, particularly for most mainstream games.
(And as a side note, LAN parties are also largely a thing of the past.)