Technically it’s never too late (until you die) to repent of a sin. America had a sin of willful blindness here. And until it worships something higher than the human machinations of government, it won’t get out of that sin. “Everybody knows” is the biggest fallacious reason for something in the book, and it’s illustrated in the classic children’s tale of the nude emperor.
But operatively, there are sins that sear the conscience to the point that the soul "cannot repent." I used to believe that as long as the breath of life is in a person, they have the ability to turn around and find Life, but I've changed my mind. Many who live on earth this day exist only to do the Anti-Christ's bidding in the Last Days.
I don't claim to know who these forever-damned living souls are, but evidence does exist to make a good guess.