Or both, that rumour still seems legit enough to me to consider, in that case it might be so unique it's a gen 1 system.

Unless it's a handheld and home console combined, it's going to be a handheld (they're not going to release a new home console before their handheld device). Handhelds don't go back 9 generations though so that's not possible. If it's a home console, it's 9th gen. If it's a handheld, it's whatever gen handhelds are in. 

Lets say that the NX also flops and Nintendo releases the NX2 on 2020 along the Ps5 and Xbox 2.

Would the Ps5 and Xbox 2 be 10th Gen Systems? Because according to some, the 9th Gen was the NX but they (Ps5 and X2) skipped that Gen entirely?

Since when Nintendo dictates when a generation starts? Specially when they releases underwhelming consoles when it comes to hardware. The Wii was a beefed up Gamecube. The Wii U is a beefed up Ps3 (power wise), rumor says that the NX will be equivalent to the Xbox One.

So not only they will be releasing a console Mid-Gen from the rest of the competition, which both of them havent peaked yet in sales and games, but they will be releasing (again) an underwhelming console from a tech perspective and still people pretend that they are somehow dictating generations?

Give me a break guys, if im being honest, i would consider the NX a 8th Gen system.

Im not the one that consider a gen by the time a system is released, more so because of the power that it has.

wow. Answering the first question: YES. although what makes you think sony and ms would be stupid enough to only release new machines in 2020? Even without a wii u successor in 2016 or even 2017, those two are likely to wait no longer than 2018 for their next consoles.

second one: No one dictates when a gen starts, time does, that's why it's absolute. the rest is a mix of lies (like wii u and NX power, mid gen launch), irrelevant claims (wii's power) and contradictions (saying power is what defines a gen, then proceeding to call a system 8th gen without knowing it's hardware).

Actually, i think the moment will help.
People like to buy new things, even when they don't need them. Just look to how people go over Iphones every year. Every fucking year.

Not saying NX will sell 9M day one like Apple's phone, but with PS5/X2 looking far away, Nintendo's new machine will get a lot of attention. It just needs to be decent and have a good marketing team.

And honestly, X1 is looking weak, and PS4 is practically winning by default because there is nothing else for you to care, so it is hard to gauge how strong it really is (honestly, i think the fandom has been weak recently).