Wii U was basically a slightly more powerful 7th gen console in it's specs (both programming language and performance), that also had a complicated marketing message and most importantly (IMO) it's exclusive games weren't really targeted towards the biggest dedicated gaming market, which are people that buy 3rd party games.
If Nintendo could make their own exclusive games targeted towards the western 3rd party audience, then they would do much better in hardware sales and actually sell decent volumes of 3rd party multi-platform games.
Hardware and software need to go hand in hand really, which is something that Sony has gotten since they started making consoles, I don't know why Nintendo forgot that was necessary.
If NX is a reasonably priced platform, with good value hardware, that also features great games you can't buy anywhere else, that will appeal to the western 3rd party audience and it also gets any multi-platform game that people could want, then people would likely buy it.
Obviously a good and clear marketing message needs to be delivered to tell people that this is what NX is all about.
If Nintendo can also do this while also adding portability into the mix I think that could be the thing that makes NX stand out from the competitions systems.
Wii U basically lacks all of this, so it's not surprising that it's sold so poorly, regardless of having a great exclusive library, if those exclusives don't appeal to the majority of people buying dedicated gaming systems and it also lacks everything else that could make them want one, well Nintendo should just own up that this is what they created and when they reveal NX they need to show they've learned from their mistakes.
