Yup, I got the ban.
I'm wondering how this affect WiiU and Switch owners. If you;re banned on 3DS does that mean you can't online play with another Nintendo console on the same account? I'm going to try it out now and fire up Splatoon...
Okay, just got into an online game on Splatoon. So it doesn't seem to affect your NNID on other devices. Oh well, then I really super don't care about not getting online on the 3DS lol.
It's not tied to your NNID, it checks against your console's localfriendcodeseed_b, which I believe is used to generate your Friend Code. For all intents and purposes, it's a console-specific ban.
If you're banned, when you go online, any service that checks against this, such as your Friends List, and most online pay in games will halt and return the error code. Since the eShop and some apps like the Badge Arcade doesn't use it, those continue to function.
Since the Wii U and Switch have their own Friend Code systems, they're unaffected by this. If you're banned, you should be able to recover if you unlink your NNID from your banned console and link it to an unbanned console, for instance if you need to retrieve Pokémon from Pokémon Bank.
I'm not certain if doing a system transfer to an unbanned console will work since your existing Friend Code is carried over. Maybe? In any case, don't do either of those unless you're moving to an unhacked stock FW 3DS until people figure out what's going on, otherwise chances are you'd just get banned again in future.