First thing's first, all three of these chapters are one big Prophecy. The modern chapter divisions weren't in the original texts, chapter 12 begins with the terminology that indicates a new Prophecy is starting and that's the last time such terminology appears in Zechariah
I'm a Futurist in my overall view of Bible Prophecy because I'm Pre-Millennial, reject the Day=Year theory, and view the Seals, Trumpets and Bowls of Revelation as affiliated with a seven year period of time the proceeds the start of the Millennium.
However there are certain prophecies I'm willing to entertain a Preterist or Post-Millennial interpretation of over the traditional Futurist ones. But Matthew 24 and the Thessalonian Epistles are not among those.
The Pastor who I do not like to name did a sermon on Zechariah 12 where even though he too is a Futurist over all, he argued that Zechariah 12 is about the time of Christ. The allusions to Jerusalem being attacked he said are only hypothetical and that the mourning is of Jesus, because The Gospels do record many people mourning him.
I do not want to link to this sermon or promote him because of the hateful rhetoric he preaches elsewhere, but over all his argument was fairly convincing. But he didn't mention how 13 and 14 are still the same prophecy, the beginning of 14 is in no way hypothetical in it's talk about Jerusalem being under siege.
He didn't mention in that Sermon what I've read about recently of how Hadad-Rimmon is thought to allude to a myth about Baal Hadad dying and being mourned, like the myth recorded in the Ugarit Baal cycle. Generally Christians reject this view, but I think it's possible that God could have been talking about the mourning to Jesus and comparing it to a pagan custom of mourning a dying god in a way that is derogatory to the pagan deity.
Or maybe one could argue the actual Hebrew meaning of Hadad or Adad and Rimmon (Pomegranate) could work as a title of Christ.
Many Jews believe it is the mourning of Josiah this future mourning is being compared to. Since Kings often had more then one name, that's possible.
Many including myself in the past have overlooked the detail of the beginning of Zechariah 14 that the Siege of Jerusalem recorded there does result in a captivity, it's not thwarted. And since Zechariah wrote this down after the Babylonian captivity, I feel the opening of Zechariah 14 makes the most sense to view as being about 70 AD.
Now critics might insist that "All Nations" gathered against Jerusalem is not literally fulfilled in 70 AD. In certain contexts what I mean when I say I take The Bible literally would not exclude hyperbolic or exaggerative language. Rome did have help from many allied and client kingdoms. Including a controversial claim that the Nubian Queen at the time sent troops to help Rome put down this revolt.
The thing I've come to accept that many of my fellows Futurists do not. Is that the part of Revelation about before the Millennium starts, chapters 6-19, feature no siege of Jerusalem, either a successful or a failed one. Not unless you think Babylon is Jerusalem, but I refute that in my Great City post and my initial Mystery Babylon post. The gathering at Armageddon is to march on Jesus at his return, not a City, and I don't think Jerusalem is where he will be till after Chapter 19 is over.
The only Siege of Jerusalem in Revelation is the Gog and Magog invasion after The Millennium. But that is entirely thwarted, there will be no captivity there.
Being Trodden under Foot of the Gentiles in Chapter 11 (that I feel we need Luke 21 and Romans 9-11 to full understand) could imply a siege happens before the seven years starts, but that's speculative. It can be viewed as still Trodden Under Foot from the 70 AD siege, due to the Muslim presence there.
It is possible that Zechariah jumps from 70 AD to the End Times between 14:2 and 14:3. But it sounds immediate, either way verses 3 and up is the most difficult part for a Preterist interpretation of this Prophecy.
I'm not sure entirely what to think yet. But I think many assumptions we tend to make about this Prophecy are wrong and more research needs to be done into it.