You'd have to refine your question. Bitcoin is already a national currency.
Pontinha recognized it as a national currency back in 2015 (they're very small, located off the shore of Portugal). I don't think that some big country would declare Bitcoin as their national currency and especially not in 2016. The price is not stable enough to act as such.
Uh...it's the "national" currency of 4 people, literally. The article said specifically, "There are four citizens: me, my wife, my son and my daughter." It's no more legit as a "national" currency that those Posse Comitatus-type folks common in the US who mount a bunch of "no trespassing" signs (usually worn-out tires) on fenceposts around two acres of river-bottom land and declare it to the The Republic of John Q. Smith.
To answer the original question, no, I don't think so, because it can't be controlled in the way that governments manipulate their currencies. For example, they can't determine for themselves how much is in circulation, can't print more to devalue it, etc...