Don't know about day 1. It depends on the price and the existence of the new Metroid game on it. Still I will buy it but maybe later

Its smart to hold off if you are unsure. Let the system prove itself first.

I'll be buying it for sure.
Not sure about Day 1 though, I'm slightly leaning towards it because of Breath of the Wild, but it'll depend on two things: Price and Launch Lineup.
If it's $249-299ish with a strong launch line up, I'll be the first one in line.
If it's $349-399ish with a 'meh' to less launch line up, I'll wait.

I have it preordered already :).

I will do that soon too

Day 1.

Probably, but I need more information before that (price, weight, battery life, launch games, other game announcements).

I never buy consoles day one. High price, infant diseases and problems, lack of proper software. I usually wait at least two years before I buy a console.
As for the NS, I need to see more of it before I decide, if it has as much handheld focus as it seems right now, it's likely not something I'll put very high on my list of future purchases, especially since it appears to have very poor backwards compatibility on top, which kinda sucks for someone who never owned a Wii or Wii U.

Most likely no. Depends mostly on launch games and price. The only console I've ever bought on day 1 was the Wii.

Probably day 1.