More difficult, but not impossible if we can find a way to completely access Wii NAND. I don't see what good could come from doing that, though
NAND means nothing in this context. You mean firmware. There are probably plently NAND devices inside the Wii....
Anyhow.. access to the firmware would allow for softmodding I suppose. Use a drive with a chip to bootstrap this code, change the firmware, put normal drive back in. But the firmware is probably, like the discs, signed.... if you had access to the firmware you wouldn't reflash it to change the region anyhow, you'd disassemble the firmware, take out a few branches here and there disabling the region lockout totally.