I see your logical point, but if they are true believers, they must obey the Commission of Christ to go to all nations. I have had this discussion many times, and your logic is good, except that if we are obedient, we do what Jesus told us to do.
Perhaps, I am not sarcastic enough for it to be recognized and should have used the marker /s
Also, Christ will not come again until He is preached to all the nations.
Most Christians want Christ to come again!