At that Passover celebration, several cups of wine would have been drunk at various stages of the ceremony, prior to the cup of wine that Jesus said was “…my blood of the new testament, which is shed for many for the remission of sins” (vs. 28) Having got their attention Big Time with such a startling declaration and invitation to partake of that particular cup of wine, Jesus then said what you quoted in your question.
You ask if the wine in his Father’s kingdom is physical wine or some other type, and why Jesus thought it necessary to speak about wine at that point.
Some people have taken the word ‘new’ to be a clue about ‘new wine’ – ‘the wine of the kingdom’. They would say it won’t be literal wine, but a spiritual kind of drink that can be enjoyed by all believers now that Jesus has returned to heaven, to be with his Father there. He returned to heaven ten days before the outpouring of the Holy Spirit upon the believers in that upper room, at Pentecost, the 50th day after Passover. Many would see that glorious outpouring as ‘the new wine of the kingdom’. Heady stuff, spiritually speaking, given the amazing effects on the believers and the resultant conversion of some 3,000 people as the believers then proclaimed the gospel of the risen Christ to those people from many countries, in their own languages.
However, let it be noted that Jesus said “with you” – requiring himself being in God’s kingdom, and the disciples also being with him, in that kingdom. Jesus will be WITH them and they with him, in the Father’s kingdom. This raises the question of WHEN this mutual drinking of wine can take place. After all, the risen Christ is still in heaven with his return to earth being a future event. Jesus, however, did not say their companionable drinking of this wine would be located on earth – the earthly kingdom of God, if you will. He is speaking of heaven because He knew, at the time he spoke verse 29, that he would be returning to his Father in heaven on the 40th day. That is why he said to Mary Magdalene on the 3rd day that he had not yet returned to the Father (John 20:17). Jesus had previously said to the disciples that he was going to the Father in heaven to prepare a place for them, “so that where I am, you also may be” (John 14:2-3) – in the kingdom of heaven, in heaven.
This is where 1 Corinthians 15:20-28 provides light for we learn that after the Day of Resurrection and Judgement,
“Then the end, when he shall have delivered up the kingdom to God,
even the Father, when he shall have put down all rule and all
authority and power. For he must reign till he hath put all his
enemies under his feet. The last enemy that shall be destroyed is
That is the point at which all things are restored to how they originally were and the fullness of the glorious kingdom of God is realised, after the Son of God delivers the restored kingdom back to the Father. Then, Revelation tells us, comes the wedding of the Lamb to his spotless bride, “And he that sat upon the throne said, ‘Behold, I make all things new.’ (21:5) That will include new wine – the wine of the kingdom – which surely shall be drunk with joy at the marriage supper of the Lamb, in heaven.
This is not to say that there is also a sense in which the receiving of the Holy Spirit by humans here on earth can be likened to new wine – the wine of the kingdom. There may, indeed, be a foretaste of the wine in heaven by those given to partake of the Holy Spirit before they get to heaven. It’s just that Jesus, on that night, knew all that lay ahead and of the glorious outcome of his death as the Lamb of God, and his resurrection, which would achieve the restoration of the kingdom of God on a cosmic scale, beyond anything his disciples could imagine, that Passover night. The wine of the kingdom, at the marriage of the Lamb, will be wine, but not as we know it! Nothing on earth can fully prepare Christ’s followers for the astounding glory of heaven, including its new wine.