The prophecy of the vine tree in Ezek 15:1-8 foretells the destruction of Jerusalem by fire.  

The Vine Tree Typifies Israel

The prophecy begins in v.2 with a comparison of the value of wood from the vine tree to the other trees in the forest.  Israel is like the vine tree in this prophecy.  

In Jud 9:8-15, Jotham compares Israel to three different trees: 

• The olive tree, as you see in Rom 11:15-18.  For example, in Jn 4 salvation is of the Jews.  Branches on an olive tree picture saved Jews.  Nevertheless, because of unbelief, some of the branches were broken off.  
• The fig tree, as you see in Matt 24:32-33, Jer 24:4-7.  The good figs typify the Jews who went into captivity in Babylon.  However, because of rebellion against God’s words, some of the figs were evil, Jer 24:8-10.  When Israel rejected Jesus as their Messiah, Jesus cursed the fig tree in Matt 21:18-19.  
• The vine tree, as you see in Is 5:1-7.  The Lord planted Israel as a vine in the land of Canaan.  However, because of disobedience against God, he wasted the vine, Ps 80:8-16,.  The burning of the bramble is a reference to the fight between Shechem and Abimelech in the passage.  Abimelech destroyed Shechem and a woman killed Abimelech.

In v.3 the Lord asked if wood from the vine is good for work.  It’s not.  He asked if it is good to use as a pin on which to hang a vessel.  It’s not.  You can use a vine for fuel, v.4, but it burns up quickly and just turns to ashes.  Therefore, it isn’t meet for any work.  And it’s particularly useless after you burn it, v.5.

The Burning of the Vine Pictures the Burning of Jerusalem

Having established the metaphor, the Lord said in v.6, “As the vine tree among the trees of the forest, which I have given to the fire for fuel, so will I give the inhabitants of Jerusalem”.  The burned up vine tree pictures the burning of the inhabitants of Jerusalem.

In v.7 the Lord set his face against them.  Then he said, “they shall go out from one fire, and another fire shall devour them”.   

• The “one fire” is Nebuchadnezzar, who in 2 Chr 36:17-19 and 2 Ki 25:8-9 burned up the house of the Lord, the king’s house, the palaces and all the houses in Jerusalem.  We see in Nehemiah that he even burned the gates of the city wall.  
• “Another fire” is a reference to the second coming of Jesus Christ.  The angel gathers the vine in Rev 14:17-20.  Jesus returns in flaming fire taking vengeance on them that know not God and that obey not the gospel in 2 Thes 1:7-9.  They are burned up, leaving neither root nor branch and they are reduced to ashes in Mal 4:1-3.  Ezek 22:18-22 describes this devastating fire of the Lord’s fury.  

Once again we read that they will know that God is the Lord, v.7.  And in v.8 he made the land desolate, because they committed trespass.

Conclusion: the vine tree is only good for bringing forth its fruit.  When it’s not fruitful, then its branches are burned, just like the fruitless branches of the vine in Jn 15.