Matthew 24:14 "And this gospel of the kingdom shall be preached in the whole world for a witness to all the nations, and then the end shall come."
This prophecy has already been fulfilled through television, radio, missionaries, the translation of the Bible into many languages, and the internet. People all over the world now hear the message of Christ from missionaries who have the means to travel the globe, and via technology that allows us to communicate with people on the other side of the world right from our own homes, churches and offices.
For the fulfillment of this prophecy, I expect to see the Islamic world be as open, at least for a time, to the Gospel as the former communist states of the old Soviet Union now are. Likewise for Communist China. It's not my sense that airwaves alone will suffice.
I'm inclined to agree with you about the airwaves.
Thanks much.