That's actually an interesting question. I don't think it will.

I'm 100% sure it will.

Nope.

But it will likely be fairly easy to port Wii U games to it, I imagine it will be a mobile chip that "absorbs" many aspects of the Wii U architecture.

So they'll be able to bring underperforming Wii U titles like say DKC: Tropical Freeze to it without much fuss.

It may be able to emulate the 3DS flat out just on raw horsepower + likelyhood of an ARM CPU.

IBM and the Renesas embedded RAM though ... that needs to go. Those are likely killing Nintendo on cost, because they're fairly exotic products (not heavily mass produced). Sony even own Renesas now, lol, so while they're unlikely to be dicks to Nintendo about supplying the RAM, they're likely not going to give Nintendo any special price breaks either, which isn't a good situation to be in. 

The sooner Nintendo can be free of the shackles of the Wii U chip, the better for them. 

Well, there aren't that many wii u titles out there so I think it's kinda pointless

It better isn't because if not it will mean that Nintendo still refuses to leave powerpc architecture behind.

So, if the NX isn't backwards compatible (and if it's a home console or the Fusion), will most of the WiiU titles be remastered? If it's the Fusion idea,they could work using the handheld as the gamepad.

If it's a home console they will probably just remaster Wii U games that didn't really use the gamepad like DKC: TF, Mario 3D World, NSMBU, Bayonneta 2, etc

If it's a the fusion, then yes, they would probably use the handheld as the gamepad

Then there is the chance NX is a handheld, in that case I think it will play 3DS games, just without 3D

It better, I want to be able to play my 3DS games or my Wii U games on their successor.

The thing with Nintendo and backwards compatibility is that they have moved themselves into a corner.
No doubt the NX will have some new way to play, but to play past games you will need a specific controller.

So imagine a Nintendo console 3 gens from now. Will be digital and fully backwards compatible, but need controller for NX games, gamepad for Wii U, Wiimote for Wii games, etc.

I like backwards compatibility but it is becoming counterproductive on Nintendos part.

What I'll say is I wish they do. Some other types of compatibility with the GamePad, like using it as an extra controller in case you need it, or maybe the ability to use it with the internet browser would be much appreciated.