It turns out Nintendo Network IDs and all of their delicious eShop purchases are not irrevocably tied to the Wii U they were created on. But before you sigh with relief and put your system back on the porch for outdoor ZombiU sessions, take heed that Kotaku reports the switch can only be made in an authorized Nintendo repair facility.
The Wii U's documentation states that Nintendo Network IDs are linked to their home consoles, meaning you can't sign into a new system you purchase or on a friend's machine. While those limitations hold, Nintendo can in fact transfer the ID from one console to another if it breaks down, but only if it's sent in for repairs.
"Nintendo of America's repair process includes the transferring of the Nintendo Network ID to a new Wii U console if a replacement system is needed," Nintendo told Kotaku.
That means if your Wii U croaks and it's loaded with expensive digital purchases (or maybe you just really like your ID), don't return it to the retailer! Nintendo won't be able to move the account from the old system to your new one, as was the case with this unlucky Giant Bomb forumgoer (opens in new tab).
We've asked Nintendo to comment on any recourse users with stolen or otherwise lost consoles may have, and will update this story with any response.