It's not like the metric system was invented yesterday and will vanish tommorrow. Change doesn't have to be instantaneous, it can be gradual over the years (and, as the article pointed out, already is)
These articles make the rounds on the internet every few months, which gives the impression change should happen quickly. But, given the enormous costs that exist to switch over, I think it's more likely we'll see a gradual change over our lifetime.
As an example, NASA is partially-metric, partially-imperial. Of course, they have that famous failure attributed to mixing units...