The Twilight Hack is old news though. The hackers already came out with a new softmod that doesn't even require you to buy a retail game to work. You just need to put some software on a SD card and install a homebrew app (which you can then use to install "backup" loaders). The Wiis produced from Mar 2009 onward though make piracy less attractive because it's a lot easier to accidentally brick your system now with homebrew/soft mod activity. Modders have to be more careful now. And the newer consoles and firmware versions have less homebrew functionality than the older consoles and firmware revisions.
The only thing I would suggest to Nintendo if they want to curb piracy significantly would be to ban modified systems from their online services (ala Microsoft's XBL banhammer). You would still have your diehard pirates who don't mind sacrificing online features to play cheap pirated games but you would still curb piracy significantly. Nintendo can keep trying to create new unhackable hardware revisions and maybe they'll get it right like Sony did with the PS3 (yes geohot hacked it but unless it starts playing pirated copies of games, there isn't a piracy issue) and PSP-3000. That isn't a guarantee but at least it's better to try rather than to give up. If the newest Wiis were unhackable, gamers who are motivated to play pirated Wii games would still be able to buy old Wiis on ebay or GameStop or whatever and avoid taking their Wii online to avoid updating the latest firmware to combat piracy. But making the latest versions hack-proof is better than nothing.