How to change countries with linked Nintendo account and NNID

Hey all,

Hoping someone may have faced a similar scenario - I've moved countries and wanted to change my Nintendo account to match my new country of residence. Thing is, I have a linked NNID attached to my Wii U and 3DS and it says that changing the country of my account will decouple the NNID from the account. I don't know exactly what this means or how to remedy it? Can I change the NNID to match? Would I be unable to sign in and access digital games on those systems if they get disconnected? Unable to redownload my prior purchases?

I'm just wanting to do what should be a very simple fix and it seems like it's been made as complex and onerous as possible.

Thanks in advance for any help