Depends what you consider a failure. Are we talking an actual failure? or the Sony/Xbox fanboys polluted baised spec peasant interpetation of a failure? Truth is Switch is a failure in almost every way in the minds of most already. Spec wise it's inferior. Graphics wise it's inferior. 3rd party support is inferior. Sales are so far still behind and it has gripes like No netflix and poor battery life along with manditory SD cards for large AAA titles. It's a failure. A collosal one at that.
But let's think realistically. A Nintendo product has never failed before. Wii U was a failure? No. It trailed PS4 and XB1 in sales. That's not automatically grounds for being a failure. People confuse losing a console generation with being a failure. Just a console from a company that doesn't spend like 1/6th of it's revenue on ad marketing unlike sony. Just a company that doesn't rely on the 3rd party heavy hitters like COD and Madden who take most of the profits for their developers anyway while Nintendo keeps most profits from their 1st party powerhouses for themselves. Let's also not mention that Wii U spawned Amiibos which are one of the most lucrative and popular interactive collectible figures to ever exist. An item not factored into total sales but Amiibo sales alone make Wii U a success. A large one at that.
But Wii U was a failure, a disaster. Everyone rallied around to kick dirt on it's corpse. Not that it didn't have 20 amazing 1st party exclusives or anything. Quality and library doesn't matter in 2017. It's about 4k and COD and what console has the most teraflops and which console had the most brainwashed consumer base to buy it's new console. So for that Nintendo will never succeed.
If failure to you is being an awful system with bad games (what a failure should mean) than the Switch will never come close to failing and already has enough catalog to define it as a success. If failure to you is based on sales and specs, two categories in which the two competitors (Xbox and Sony) have manipulated and conquered the entire market and demographic to easily win every time. And we'll sit around and stress how PS4 is a better selling console than Switch. We will definitely see Nintendo as a big fat nothing. A loser. A company bound to death and mediocrity.
But the fact is. Switch is a master class system. An elementalist super beast with one of the best launch libraries in history. And it's a success in the minds of most. Just like the Wii U. But the user base isn't as large and the Xbox/PS4 hate train is too toxic and strong for Nintendo's current legacy to be anything more than a failure. It's sad but it's the state of gaming now