Ezekiel 15 and John 15: Jerusalem and Jesus

And the word of the LORD came to me: "Son of man, how does the wood of the vine surpass any wood, the vine branch that is among the trees of the forest? Is wood taken from it to make anything? Do people take a peg from it to hang any vessel on it? [Answer: no] Behold, it is given to the fire for fuel...
Ezekiel 15:1-4

What's the point of Ezekiel 15? Answer: John 15.

I am the true vine, and my Father is the vinedresser. Every branch of mine that does not bear fruit he takes away, and every branch that does bear fruit he prunes, that it may bear more fruit...Abide in me, and I in you. As the branch cannot bear fruit by itself, unless it abides in the vine, neither can you, unless you abide in me. I am the vine; you are the branches. Whoever abides in me, and I in him, he it is that bears much fruit, for apart from me you can do nothing.
John 15:1-5

Though it appeared as though Israel was the vine in the Old Testament, the point all along was that the coming Messiah was the true vine. Though that vine withered and faded, Jesus never will. And it's only by abiding in His person and work that we will avoid experiencing the same decay that Jerusalem did. Because--quite literally--apart from Jesus, we can do nothing.