I think Nintendo is confident yet cautious. They likely have a winning product, that isn't even a question honestly, but rushing the thing is the exact "pride before the fall" mistake that Nintendo has made on 3 occasions. The launch of the N64, 3ds and Wii U. All successors to big systems for them, all of which suffered from being rushed or heavily flawed as a result of previous successes. Taking their time is sensible, getting everything ready to ensure no screw isn't tightened.
If I had to describe what Nintendo is doing in a brief gif, it's as simple as: