I’ll have to read it later, but usually, the Old Testament prophets aren’t talking about eschatology, they’re talking about events within the years following their predictions, and then later people anachronistically apply every little thing to the end of the world.

There are some exceptions to this but as a general rule, I’m skeptical when anyone says an Old Testament prophet is talking about current events. 

 @Aspartame @Caek Islove 🍰 💖  @Moved @Quentel 
It's about future events, because "in that day" sounds like the day of the LORD, and the proceeding verse (10) matches Revelation 1:7.
Isaiah 13 likewise links the destruction of the armies of the nations to Christ's return (celestial blackout in verse 10) 

 The 2nd half of Zechariah 12 is about Israel mourning the Christ, so I agree, it seems to be saying that jews will convert after Christ saves them from destruction.