It was an ineventable decision that was likley to happen, but Nintendo dropping the Wii U to release a 9th Gen console earlier makes such a move less exposed to be critisized in the media.

I remember when Sony released a PS4 just because they were scared of the Wii U. Thankfully Nintendo is really shaking up the industry, always giving their competitors stuff to fear.

This gen and the last have proven that there are a lot of "swing" buyers with not too much loyalty over consoles. Nintendo hits the market with a more powerful console (like the PS4 to the X1), with must have exclusives ( much like 360 in the beginning of the gen comparably mass effect, gears..) At a competitive price?

It isn't the sole reason or even perhaps a major one, but.... Why take the risk? The internet is on fire with NX speculation. It isn't just here.

Lol yeh, because a rumor basing itself on another rumor is anything of substance. I'm also sure the PS4 is trembling in the NX's looming arrival...

PS4k is confirmed and well, NX is all but confirmed. Why not speculate. It's what forums are for.

This is probably the best conclusion as to what is really happening here. Sony probably was toying around with this idea back in early 2015 (probably late 2014 as well) and the Nintendo comes out of nowhere announcing the NX. Sony goes "HOLY SH*T" and they start pushing this console through production so it could make it out just in time for the NX release. I'm not expert on the time thats needed to make a video console, but if this really is just a PS4 with a 4K upgrade no more no less, then I don't see how this console could have taken more than 2 years to develop. Especially if Sony started to push it through development.

So tl;dr Sony was probably working on it but the NX announcement caused Sony to push the PS4K through production for a 2016 holiday release. That's at least where I'm standing right now until we get an official announcement.

I don't think so. Andrew House talked about a middle gen hardware before the release of PS4, and if PS4N will be true, i think it's in developement before the rumour about NX.

Maybe in some way, but I doubt that was main reason that Sony goe with PS4.5.

VR influenced PS4K.

I seriously doubt Sony or (to a lesser extent) Microsoft is worried about anything Nintendo is doing.