Actually there really isn't a way to lose all of them. You can't install stuff to SD in Wii U or in vWii, so you'd be fine if you switch. The only way to lose files is if you unplug the USB that you install titles on.
sorry, beein trying to find this file that's been right in front of me for a month now, only to find broken links, and google to prove that it's completely worthless.