Yeah, about the dock...I've been thinking about another possibility for its usage. So, we know that's where you'll put the screen on, in order to get the game on the TV, possibly (this is speculation) at full clocked processor + venting system to avoid the unit overheat (especially considering how it needs to be handheld for handheld "more").
However, that other tweet from EG's Tom Phillips, the guy who posted the NX's pic of concept...
https://twitter.com/tomphillipsEG/status/757966907542761472
Some people here mocked at him, but, I wonder if it's possible that...
On Wii U, it's the stationary console that sends two signals, one to the TV screen through HDMI and the other through streaming on the gamepad (480p here). The screen on the gamepad can output the exact same screen the TV is outputting, or something else, like menu / options / map / etc.
I can see the possibility NX does this as well...but in reverse. It's the handheld that, while outputting images on its own screen, streams the signal to the dock that, connected to the TV, will show the game (in this case, the signal sent through streaming should be at an higher resolution, and I wonder how much that is fiesable from the handheld, even a seemingly pretty powerful one). Of course, that would be a way to play games that wouldn't allow to use the full power of the device, unlike (if our assumptions are correct) when docked. However, dual screen gameplay would be enabled: this is how Splatoon could work as it does on Wii U, or other titles like Etrian Odyssey where the bottom of the screen is very relevant.
Again, I wonder if such a thing is fiesable in this context.