I remember the days of 2015 that this forum were taken by NX speculations.

Its based on another rumour, so this is 100% inaccurate.

Okay... this is confirmed then, a customized Tegra X1. RIP

For GPUs, yeah he really meant that.

http://venturebeat.com/2016/02/16/mobile-devices-will-be-more-powerful-than-playstation-4-xbox-one-in-2017-arm-forecasts/

He mentions nVidia...

Not saying he's right - but all things considered when Tegra X1 launched in 2015 it was significantly better than 360/PS3 in terms of raw GPU performance.

What do CPU and these other things mean? I mean, I know what a CPU is, but what does a weak CPU mean in practice?

Actually it doesn't mean anything. Both X1 and P1 use A57. Whether or not they are the modified Denver cores is what counts and ARM wouldn't know that information, since it is nVidia that did the modifications.

Plus also pointed out in the video in the original post the Facebook "leak" was a link to a speculation piece based off of a speculation piece and not a direct up announcment from ARM. It just seems the social media manager(s) at ARM got a hit on an article that talked about ARM and decided to post it.

No Denver cores in X1

http://www.greenbot.com/article/2879437/everything-you-need-to-know-about-nvidias-new-tegra-x1-chip.html

It's just meant to be 4 Arm A57's at 1ghz, the big cpu's of the big/little arrangement of a standard X1 but they are only running at 1ghz.

This was announced at some developers meeting about the Switch that was leaked to eurogamer and the Arm leak reinforces that as the likely cpu arrangement although the hz speed wasn't mentioned.

I think it's highly unlikely this is incorrect. 

Looking forward to reading a teardown of a Switch, I think 2GB memory is still a possibility despite 4GB being more likely according to the rumours.

Why "RIP"?

A system's CPU is typically responsible for processing tasks such as game logic, AI, animation, physics, etc.

Having a weaker CPU means a system will be less capable of running games that push loads of characters at once, complex physics, etc.

Fatslob is the last person you need to remind them of that.

The thing with the PS4 is that, although on a per-core basis it is roughly equal/maybe even slightly worse performing than the A57 on a Core to Core + Clock for clock basis... The Playstation 4 gets away with the fact it simply has more cores to play with.

But with the A57 clocked at 1ghz, no doubt in my mind that a 1.6ghz Jaguar Core can soundly beat it.

Jaguar should be a little worse in IPC.

Volta based Tegra should be competitive with the Xbox One.

The most visible things would be...
less complex and sophisticated Artificial Intelligence.
It means less CPU-based Physics calculations. (Think cloth or leaves waving in the wind.)
It makes CPU driven effects such as Anti-aliasing, less likely. (Nintendo is allergic to using Anti-Aliasing anyway.)

There is a ton more to it though.

I know right, it was weird enough on Wii U, but to see games like Splatoon 2 and Mario Kart 8 Deluxe still having no AA on Switch, even when docked, is just bizarre.