With obvious shit out of the way, I think its demise is really due to Nintendo's issue as a whole these days with relying on its own IPs to sell consoles. AA devs don't really exist anymore so now can't have another console like the Wii with a huge library of games to take advantage of the console's gimmick. That time is over and even though a lot of third-party Wii games were trash, the console still has a better library than the Wii U and Switch combined. Instead, you just have indieshit that's available on every system and some ports. Also, the Wii U never had a strong launch title like the Wii and Switch did.