I think your are right, Syria and Iran are going to panic. Iran's is going to hit Israel before this ends.
What better provocation for Israel to take out the Mullahs and their nuclear program by launching a massive nuclear strike on Iran. They will be condemned by many but that should bring to an end hostilities from outsiders.
The only way Iran can directly strike Israel is with a Shahab-3 missile. Iran would have to move those missiles into position very close to the Iraqi border. Any activity like that would be noticed immediately and likely dealt with, given the current threats issued by Iran to Israel. The Arrow system is the Israeli equivalent of our Patriot PAC-3. I believe Israel is preparing for every contingency.
With what? They have no aircraft capable of reaching Israel, and if they did, they'd pretty much have to cross either Iraq, whose airspace is controlled by the USAF (and other coalition forces), or over the Persian Gulf, which is controlled by the USN (and others). Can you say, "Great Gulf Turkey Shoot"?
Iran might have missiles with enough reach, but most likely has no nukes to mount on them, yet that is. If they shoot chemical weapons or conventional HE, there will be no restraint of Israel by the US this time.
No doubt about it.
Iran cannot sit idle as Hezbollah is systematically, and completely, destroyed. It will reduce their credibility to virtually zero with their fellow Islamicists.
They MUST respond, and they must respond with Iranian-flagged military forces. It'll be fun to watch...