This thread is pretty much what I expected it to be. You even managed to mess up the easiest point of them all, the games.
3. Marketing of a console is a subsequent factor, not a decisive one. The typical analyses on gaming forums conclude that marketing is front and center, so a console that sells well is considered to have good marketing while a console that struggles is perceived to have bad marketing. But what's really going is that the console itself is either good or bad, so the appropriate conclusion for Switch and Wii U, respectively, is that Switch sells because it's a great console and the Wii U failed because it sucked. The marketing, regardless of its form and quality, doesn't change those fundamental things. And while the two SKU at launch strategy of the Wii U was stupid, it wouldn't have changed the fortunes of the console if there had been only one SKU at launch.
2. The typical arguments about core audience tend to miss the point by a huge margin. When you take a serious look at the bestseller list of the NES (which is what defines Nintendo's core audience), you'll see virtually all of those games that the modern gamer defines as casual and non-core. The NES had a mixture of bringing arcade games into people's homes (so games that were understood quickly and could be played in short bursts) and creating games that had longer play sessions. Does Wii Sports on the Wii really qualify as non-core when the NES had Tennis, Golf and Baseball as multi-million selling games? And what about the Virtual Console that the Wii had from day one, was Nintendo trying to appeal to casuals? What about New Super Mario Bros. on the DS, is that a non-core game?
All too often the modern gamer has the idea that Nintendo's core audience are the people who bought the Nintendo products that led to ever-declining sales, but that's completely backwards. Those failed Nintendo consoles actually show that Nintendo didn't properly cater to their core audience. The games that Nintendo's core audience likes shouldn't be looked down upon; while the modern gamer pretends that those people want easy to win games instead of real games, the reality is that it is about games that cut the bullshit that wastes people's time.
There's this messed up idea that the Wii U catered more to core gamers than the Wii, an idea that is based on assuming that the core gamer is the person who plays FIFA and other stuff that the AAA industry churns out. While that audience is the core audience of Sony and Microsoft, it's certainly not Nintendo's core audience because Nintendo was never the place to play those multiplats. Pretty much all hit games on the NES were exclusives and that carried over to the SNES; the Genesis/Megadrive was the console that housed the precursor of today's multiplat gamer and from there it moved on to the PS1.
Switch's signature title is Breath of the Wild. With Switch Nintendo did indeed return to cater to their core audience and Breath of the Wild's core is the original The Legend of Zelda, not Ocarina of Time. This is something that should make people think. For the longest time Ocarina of Time and Twilight Princess (based on OoT) had been the best-selling Zelda games of all time, but now that the original vision for the Zelda series got its first modern interpretation, it's blowing the sales of OoT and TP out of the water. Not only individually, but also combined.
1. You close out your post with the implied importance of AAA third party games despite Switch's success clearly not being based on them. It's one last effort of yours to make the puzzle fit that AAA third party is core despite their sales matching indie games at best. Nintendo's core audience does not need a more powerful Switch, because the core gamer of a Nintendo console is very different to the core gamer of non-Nintendo consoles.
EDIT: I wrote my own thread why Switch is a success.
It was posted about three weeks before Switch launched.
The core game for Nintendo system are arcade games easy to learn hard to master. With Sega and Atari down, Nintendo is the only sucessor of this core type.
The core game for Sony and Microsoft are computer games heritage. EA, Rockstar, and other major thirds born in PC game.