John Gill Commentary Zechariah 8:20

"Thus saith Jehovah of hosts: [It shall] yet [come to pass], that there shall come peoples, and the inhabitants of many cities;" — Zechariah 8:20 (ASV)

Thus says the Lord of hosts, [It shall] yet [come to
pass]
This is another thing that shall certainly be accomplished: that there shall come people, and the inhabitants of many cities ;

in the Gentile world; they shall come and hear the word, believe in Christ, and join together in a Gospel church state; as they did at Antioch, Thessalonica, Corinth, and many other places:

Ben Melech says this shall be in the days of the Messiah; and so it has been in the days of the true Messiah Jesus, and will be again in the latter day.