It will matter to Israel
You seem to be missing some vital background knowledge -
All Islamic extremist terrorist groups in the Middle East share a fundamental jihadist ideology -
They differ on cultural and secretarian grounds but they all have an existentialist, fundamentalist approach to Israel. It doesn’t matter whether they are Hezbollah, Al Qaeda, Hamas, Houtis, Palestine Jihadists or ISIS etc
Yemen is a good example of extremist groups exploiting a civil war:
AQAP, ISIS-Yemen, and Iran-backed terrorist groups such as Hizballah and the IRGC-QF continue to exploit the political and security vacuum created by the ongoing conflict between the Republic of Yemen government under the leadership of President Abd Rabu Mansour Hadi and Houthi militants, as well as the ongoing south-south conflict between the Republic of Yemen government and the Southern Transitional Council (STC) - exactly the same pandora scenario will happen in Syria in the political vacuum left by al-Assad.
Iran is a State Sponsor of Terrorism throughout the ME not just Hezbollah:
Supporting Hizballah, Palestinian terrorist groups in Gaza, and various terrorist and militant groups in Iraq, Syria, Bahrain, and elsewhere throughout the Middle East. Iran uses the Islamic Revolutionary Guard Corps-Qods Force (IRGC-QF) to provide support to terrorist organizations, provide cover for associated covert operations, and create instability in the region. Iran has acknowledged the involvement of the IRGC-QF in the Iraq and Syria conflicts, and the IRGC-QF is Iran’s primary mechanism for cultivating and supporting terrorist activity abroad.
Antisemitism is a core part of fundamental Islamic ideology and Iran backs a plethora of terrorist groups with that ideology not just Hizbollah.
Iran also backs Russia and China who both have influence and stakes in Syria - Russia was already involved in bombing rebels to prop up the Assad regime - US and Russia will be heavily involved in what happens next.