Juan Cole offers some predictions:
2013 will see Iranian influence in the Middle East continue a decline that began with the Arab upheavals of 2011. Iran’s two major allies in the Arab world are Syria and Lebanon. In Lebanon, Iran arms the Shiite party-militia Hizbullah, and does so overland through Iraq and Syria. Since Israel controls the Mediterranean off Lebanon and can, when it wants to, control Lebanese air space, the land corridor for Iranian supplies to Hizbullah is key to the latter’s ability to confront Israeli expansionism into Lebanese territory.
Hizbullah could well have its Iranian lifeline cut. Its secretary-general, Hassan Nasrullah, has come out strongly in favor of the government of Bashar al-Assad in Syria, because both of them are Iranian clients. If Syria falls to the Sunni Arab revolutionaries, the latter will have a grudge toward both Iran and Hizbullah for supporting the Baath government, and will likely cut the latter off from resupply through Syrian territory. Instead, Syrian support will go to the Sunnis of Beirut, Sidon, Tripoli, Akkar and the Biqa Valley.
Between 2003 and 2012 the United States, in a fit of absent-mindedness, made Iran a regional hegemon. Washington overthrew the Taliban in Afghanistan and delivered it into the hands of the Northern Alliance, a set of strong Iran allies. A brake on Iranian influence in Afghanistan was removed. Then the Bush administration overthrew Saddam Hussein, the Sunni ruler who subjected the Shiite majority and stood as a barrier to Iranian penetration of the Middle East. Without meaning to, the US brought to power a religious Shiite government that naturally allied with Iran. Then the US Congress targeted Syria for deep sanctions and the Bush hawks drove it firmly into the arms of Iran. The Bush administration backed Israel’s attack on Lebanon in 2006, which strengthened the Shiite party-militia Hizbullah, which now is a key backer of the government of Lebanese Prime Minister Najib Miqati. The pro-Iran capitals stretched from Kabul to Beirut (light blue in the map below), and Iran suddenly became a much bigger player in Levantine affairs than it had been in the 1990s. The Israeli security establishment, indeed, fingered Tehran as their most pressing threat. Iran was lionized in the Arab world for supporting Hizbullah against Israel in the 2006 Israel-Lebanon War.
If al-Assad falls in Syria and is replaced by a Sunni government of revolutionaries, they will be beholden to Saudi Arabia, Qatar and Turkey (and Libya), all of them Wahhabi or Sunni powers. They will likely punish Hizbullah for its support of the Baath government, and will support Sunni forces, including the Muslim Brotherhood, in Lebanese politics. If Hizbullah can’t replenish its stock of rockets, its geopolitical significance could decline, even as that of the Sunni Muslim Brotherhood rises. The partitions in the following map, of Iraq and Afghanistan, are meant only to depict the regional divide over foreign policy, not to suggest an actual break-up of these countries (but who knows?)