Apologies, my above explanation is actually wrong. The article is actually referencing the margin of the candidate. So it was a 82 point margin between Clinton and Trump in 2016, which is still difficult to interpret because it doesn't mention if this includes 3rd party votes. But assuming 98% of voters voted Clinton or Trump, this would mean that 90% of black votes went to Clinton and 8% went to Trump in 2016.
This would then mean that if 98% vote Trump or Biden in 2020, we'll see something like 84% of the black vote for Biden and 13% of the black vote for Trump. A 5% overall change using 2016 voter participation numbers is still somewhere around 700,000 vote change in the black vote, which is certainly not insignificant. Adding in the change in the Hispanic vote (a margin change from 37 points in 2016 to 23 this year), this could certainly change swing state outcomes.
