Exactly, something like this would take up so little resources that even lukewarm sales would likely turn a profit.

People loved Guitar Hero too .... 12 years ago.

Fads generally don't come back after 12 years.

Do you ever think that Nintendo releases these games because their developers like making them, rather than chasing a supposed fad? Like these games must do well enough for Nintendo to keep letting the teams make them.

In order to ensure Switch had a killer first year and didn't suffer the Wii U's fate of launching into a protracted drought, Nintendo opened fire with almost all their big first party teams (Zelda team, 3D Mario team, Mario Kart team, Splatoon team, Monolith Soft) in 2017.

The cost of this is that since big games these days take 3 years or more to make, those teams couldn't have another game ready for 2018 or this year. Next year however, is when we should see these teams start to release their second generation Switch games.

You can also get Fire Emblem, Mario Kart, Pokemon, Mario Bros, and countless knock offs of those games, as well as shooters, fighters, sports, and pretty much whatever else you want on a phone for 0 dollars.  That really hasn't stopped those things from succeeding on consoles.  If it's a good product that's marketed well, it'll do fine.  

Fixed that since you seemed to be making a very broad conclusion based on one data point.

Also remember, that many of Nintendo's other developers we're still on 3DS games too, so that Complicated the situation. 3DS is done now, so Nintendo has more resources to work with for Switch ganes

I actually enjoyed Big Brain Academy on Switch more than Brain Age and feel like that'd be a better fit on the Switch, but still might get it as I assume it'll be fairly cheap and come bundled w/ a stylus (which will also be useful for Terraria Switch)

For all four maybe. But only one of them sold more than 1 million units (the Toy-Con set). The rest performed horribly. Remember that this was a product Nintendo touted as expending the user base and they heavily advertised. It sold worse than Nintendo's more niche titles like Fire Emblem and Xenoblade

That's a good point and it's kind of what I'm thinking. Still, Nintendo has more studios than those that released stuff for 2017. Nonetheless, 2020 could be a huge year for Nintendo.

Yeah 2020 could be massive, personally I'm hoping we get BOTW2 and/or the next game from the 3D Mario team. (Fingers crossed for Galaxy 3) 

I want that stylus for Mario Maker 2!