I think everyone is cautious about the NX/Switch.
For one, it's a new console being released completely out of sync from the other consoles. Typically there is a big reveal at e3, and all 3 major consoles release at the same time. It's been that way since the PS2/Gamecube/Xbox, PS3/Wii/Xbox360, and PS4/WiiU/XboxFail. This might make people feel like the Wii U died a little bit too early, even if it was around for awhile.
Not only that, but it's both a Console and a Handheld. This naturally makes every fan feel a bit awkward because it feels like a replacement for both our 3DS and WiiU, and the 3DS was a pretty beloved handheld. We really don't want the things we've grown so attached to die.
Realistically, I think the 3DS and NX/Switch will co-exist.
Also, I think the NX/Switch will be a critical success to Nintendo since it is the perfect console for social gaming; it always has 2 controllers, it's portable, it's a true tablet. Just like it showed in the trailer, a bunch of guys were playing Sports games at a bar. Parents will want it because kids no longer have to use the TV, and adults will want it for the more mature library of games, such as *portable* Skyrim.
My only complaint is I do not see a D-pad on the console. WTF? This is by far the most controversial decision. Not only will it negatively affect classic gaming, but it's sort of a betrayal to everyone who stuck with Nintendo for 20+ years. In each and every console they've made, they've always had a D-pad. I am very worried about this.