Probably been stated before, but oh well, a bit of confirmation:
Nintendo can't brick it. It's illegal.
Even if you hack a system to do illegal things, they're suddenly not able to commit a crime. And violating the EULA doesn't give them the legal right, thankfully, to brick a system. EULA =/= Law. Once you buy a system, you are in ownership of it and can do to it what you please. Plus hacking it in the first place isn't illegal - running pirated content is. However again, that said, Nintendo are in no legal position to do the bricking.
Source? Lawyer friend.