In the future, God is going to kill Leviathan, the giant sea-dwelling dragon.
He's also going to tend a vineyard (the people themselves). If the vineyard yields good grapes, God won't destroy it. If it doesn't, though, he will. So, he wants there to be peace.
Israel will be like a blossoming fruit tree in those times.
God will punish the people before he does all these nice things for them. He will purify them through destruction and obliterate all the sacred stones and trees they've set up.
The fortified city will be totally devastated. Calves will graze there and women will gather firewood. And that's because the people who used to live there just didn't know what was up, didn't follow God's will.
God is going to gather together everyone in Israel, from the Euphrates to Egypt to Assyria. All these exiles will finally come home and worship God on the holy mountain in Jerusalem.