Nintendo have released a new Wii U system update, after not updating the Wii U since January 2016.
The only thing Nintendo state has changed is in firmware version 5.5.2 is "Further improvements to overall system stability and other minor adjustments have been made to enhance the user experience" what this translates to is patching the web browser exploit used to gain access to homebrew.
Surprisingly however the IOSU and Kernel exploits have not been patched, just the web browser entry point required to install these exploits.
So if you have followed Digiex's Wii U Permanent Homebrew Channel / Launcher Exploit Tutorial [Haxchi 2.0 Wii U Hack] and installed the Homebrew Channel to a DS this should still work fine, as should all your homebrew.
Haxchi and CBHC work as normal if already installed.
However I would still suggest not updating, as you gain nothing and lose the only way to ever install the Homebrew Launcher in the unlikely event you mess something up at a later date.
If you followed the tutorial linked to above you should have already blocked your Wii U from auto updating, if not then follow this guide here to block Wii U System Updates if you care about Homebrew and Hacks.