It's interesting to think about how the proliferation of other devices could protect the security of consoles. What use is there really for cracking them open other than piracy when there are so many other devices that can do the things you'd want homebrew for? The only particularly interesting thing about the WiiU's hardware is the gamepad, and if that can be used with a PC, what's left?
I'd say the 3 biggest uses I'd find are:
- full digital backups of retail games. That could essentially be used for piracy but a legitimate user could just buy physical copies of games and rip them themselves, if only to avoid buying digital stuff from Nintendo. I know I'd be in that case as a user as I've been with PS2 and Wii (buying my games and copying them to a HDD).
- region unlocking. Self explanatory. If not, read the xenoblade threads from when the game released in Europe. Or read any Persona 4 Arena thread.
- fan translations and patches.
- XBMC. I currently use it with my PC+ iPad but having it in WiiU could streamline the process a bit more. No piracy here, I use it mostly with my ripped DVD collection (for convenience and space).
These probably don't look like much to most people but I'd definitely have uses for a fully developed home brew scene. The worst possible scene would be one where only pirates would find uses for it.