I'm a huge Nintendo fan, grew up with the Game Boy Color and so on, and I'm probably going to get the Switch day 1. I ride with Nintendo I die with Nintendo.
That being said, I don't think the Switch will do well outside of big Nintendo fans because they aren't offering anything that will appeal to other people. Sure, I think Nintendo is great, and makes spectacular games, but that's not how the rest of the gaming ecosystem sees them. The rest of the gaming world looks at the Switch and sees a weak, odd device that doesn't really know what it wants to be, with, well, nothing big and hype coming out for it on launch other than Zelda, that also costs 300 bucks, that has no free online, no bundled in Pro controller, and so on. I gotta say, the Switch is a real hard sell to people who aren't already big Nintendo fans, and I'm saying this as a big Nintendo fan. It's really too bad, because I wish Nintendo would do well, but I think the Switch will be a really hard sell, unless they pull something like what they did for the 3DS, with a big price drop and ambassador-program things up or something like that.
Anyways, I do at least think it will do better than the Wii U. I think the Switch has a lot of potential to be great, so I hope things go well.