You're right, the One did have a good launch, but because of a end of the year launch, and it was shadowed by an even better launch by the PS4. The console's image and the following months were pretty bad though (at least compared to the PS4 IIRC). The numbers of the launch day itself are not that important (especially with several months of hype and pre-orders), it's the launch period (the first few months) that matters. If the NX doesn't build a good first userbase and image between March and October, the first Holiday period could be complicated. And if the first Holiday period is bad, then everything following could be bad too... 

I still think that the launch between the PS4 Pro and the Scorpio is terrible and that the only thing that will save the NX will be the handheld market... 

Wasn't the NX supposed to go come out this year? Delaying a second time would be a bit too much. Which is why I can see it happen.

Yeah - I think march is still going to happen.

I think their fear is showing NX's portability will somehow cannibalize the recent uptick 3DS sales. But by the same token they want the NX reveal to be fresh enough in people's minds and launch soon enough that they consider it an alternative to PS4/X1. This is why they're revealing it as late as possible.

Additionally, it's not that they're unable to reveal the NX - they just want to be very, very clear what the system is and what it does. They also need to make clear right away they haven't repeated the same mistakes as WiiU.

The WiiU by comparison largely grew stale in everyone's minds long before PS4/X1 even launched. The WiiU came out too early into the spotlight with a middling message. The NX instead will come at a time that feels late, but with an overwhelmingly clear and positive message.

I believe it because Nintendo said it would. So yeah... I'll go with whatever they say.

Would not surprise me one iota if it is delayed.

Because there's more than enough time, and the official information we've received so far supports that.

Because Nintendo already said themselves that it would be.

I'd imagine a reveal in November / December and a launch in March.

However it is possible it will be revealed in March and launched Fall 2017.

I refused to read anything but the OP.

To the best of my knowledge, Nintendo has never announced a specific launch month for hardware and then delayed said hardware.

With that in mind, NX is coming in March.

I agree. They have more options than ever before to promote the new console and its software (additionally to the classic advertise channels):

Nintendo could add a small app to their next 3DS and Wii U firmware updates like "What is the NX" with pictures and informations and explanations of the unique selling points of the new device. That would inform tens of millions Nintendo gamers for free.

They also can add these informations to Miitomo. They can make it playful, perhaps a quiz about the NX-features, which earn coins and tickets. Another few millions users informed who like Nintendo.

Then we have Pokemon Go... another app which could be used for NX-advertisement and which will reach millions over millions of people.