I wouldn't consider 3DS a failure since it has sold 80M units in an era where competitors are phones and tablet, see Vita.They followed up Wii and DS (their best selling console/handheld, respectively) with Wii U and 3DS (their worst selling console/handheld).
Wii U was such a disaster it’s a miracle the company even survived. 3DS flopped initially, but recovered once they dropped the price and released the XL version.
Iwata brought the company to a commanding lead, then totally squandered it so badly it almost killed the company. I don’t think there’s ever been another reversal of fortune that huge and dramatic in the gaming industry.
I guess kudos to him for whatever he had to do with the Switch. But I remember every video game pundit and analyst screaming at the top of their lungs that Nintendo should just make a damn hybrid console/handheld. It’s not like Switch is some moonshot that only the geniuses at Nintendo could’ve come up with. It’s a freaking Nvidia Shield tablet that with controller attachments.
WiiU was a failure, for me a worse failure than Virtual Boy. Shit happens, and arrogant Nintendo is always coming when they think they are at the top of the market (N64, Gamecube, WiiU). But in the end, WiiU brought enough money to Nintendo they eventually didn't consider it a console that generate some loss.
Switch is a product everyone could do but eventually Nintendo did first, and did it well, you need some talent for doing this.