Isn't it the same as with every other entertainment system? I grew up with a big brother and a little sister. We only had one PS1, later one X360. We could either play in co-op, or take turns. Sometimes my father would also play on the console, and we'd do something else in the meantime.

What's different about the Switch? It's an entertainment system. You insert the game, you play. I don't have one, but I'm pretty sure it allows for different accounts to be created and each have their own save file, so there's no need to buy multiple consoles/multiple copies of the same game. You can either play on the go, or hook it to the TV and play with the bigger screen. You are not forced to play party games just because you have a bigger screen, and you are not forced to treat it like a "personal device" just because you are playing on the smaller screen (I also despise the idea of "personal device" for kids: learning to share games is a very important lesson for kids).