Perhaps.But I'm debunking your ideology of all have heard the gospel. To say 100% of BILLIONS have heard is utterly ridiculous.
But consider just a minute our responsibility to our generation only. After all we are responsible for it, and it also has the greatest population at any time in history.
Is it possible that every person at least has the possibility of hearing the gospel at least once in their lifetime? Will they encounter that possibility, or to put it another way, if they had the desire would it be impossible for any person not reach the gospel in some manner?