Hm. Well, someone has made me an offer for my current Wii U that I can't refuse, but I would really like to be able to use my current ID on a different console in the future. Not necessarily the same account, just the same username. I'm okay with losing my current account as I've only paid for one $10 digital game, but I would really like to be able to use the same username that I'm now using on everything else that I... use.
Again, I'm okay with losing the account, I just want to be able to make another account in the future with the same handle. So I guess my question is, if I delete that account, will it "free up" that particular username I chose for that account, pending that nobody else takes it between now and whenever I get a new Wii U on down the line?