Nintendo isn't ready for next gen.

[PAOerfulone]

They don't need to do something over the top. They just need to learn from the mistakes they made with Wii U, by doing the following?
1) Give it a new name that will be easy to recognize and people will know what it is when they here it. People still think that the Wii U is just a tablet add on to the Wii, if it was at least called the Wii 2, it would be selling more than what it is now. But I definitely think they need to scrap the Wii name entirely and go for something fresh.

2) Market the damn thing. Give it proper marketing and advertising so that people everywhere will actually know what it is, and where to get it. When the PS4 and Xbox One were approaching their launch, every other TV commercial in between sitcoms or sports' games would show an ad for one of the two systems.
Splatoon's marketing was a step in the right direction, now they need to do that on a bigger scale for NX.

3) It NEEDS a strong launch lineup. I've been predicting that all of their main projects and heavy hitters that they're developing or planning right now, except Zelda Wii U, have been moved to NX to help give it a strong launch. Which is the biggest thing it needs if it's going to have a chance to do well. Plus, it needs to be back by a solid lineup of many 3rd party games supporting their high quality 1st party stuff. (Though, I'll agree with the OP's 3rd point, that they don't have a good relationship with them, so that's going to be the toughest one.)

They need to get back to where they were with the Super Nintendo, strong, high quality 1st party games, with a decent quality of 3rd party games to back them up.