I'm really curious what this means in the larger context: does it refute the fundamental evidence that Norsemen reached the New World before Colombus, or is there enough other evidence that this is no big deal?
Archeological evidence found in the 1960s proves quite clearly that Norsemen reached the Americas 500 years before Columbus. In fact this evidence turned up - and got quite a lot of attention - in the 1960s, which is when this map was first published. But by the 1970s, analysis of the ink made it fairly clear it was a forgery.
This news is just that a more detailed analysis has been done, proving the map long believed to be a forgery was definitely a forgery. But the map was never really considered evidence of anything in particular; it was always questionable.
This doesn't change any understanding of history.