I'll say this: it's not the success it is said to be.
There are several things that make Switch only a temporary success.
First, i woudn't lump both 3DS and Wii U sales together: there was some overlaping in sales and they were two distinctive consoles: Switch doesn't necessarily take all the strengths from the handheld and home console sides of it, to appeal to both sides.
Switch has yet to get a BIG 3rd party game outside Fifa, that isn't a port and not an online game (not to take merit away from them).
Mobile business is here to stay even if Switch was clearly outselling PS4.
Honestly, the only way i see Nintendo giving out on the market would be if they failed after several attempts (not happening).
The only structural change that i have seen is Nintendo bringing online games like Fortnite, Arena of Valor, Warframe and Paladins, to the console. Even then, they have so far failed to make a game of that genre to really attract those type of gamers.
In terms of 1st party titles, i'm not sure if they have passed the Wii U by now.