Zechariah 14:16 envisions all the nations going up to Jerusalem to keep the "feast of tents" (Tabernacles). Historically, this was the harvest festival where Israel celebrated God’s provision and His "dwelling" with them in the wilderness.
The true Feast of Tabernacles is not a future event in a physical city, but the present spiritual reality of the Church. When John describes the New Jerusalem, he says, "Behold, the tabernacle of God is with men, and he will dwell with them" (Revelation 21:3). We keep the "feast" today by enjoying the spiritual harvest of souls and the permanent, indwelling presence of God through Christ. There is no more need for literal booths; we are the dwelling place of God.