No doubt, Israel can take care of Syria. The Syrian military is about as adept as the Wal-Mart Parking Lot Security Force. Iran is the real problem. Iran has orchestrated this scenario. They have been itching to destroy Israel. Even if they cease this attempt, they will try again and again, until they succeed or until someone destroys Iran.
While I agree with your point, this is the way I see it playing out which leaves Israel free to concentrate on Syria.
1. Things finally escalate to the point that Israel starts taking out Syrian military assets.
2. The US stays out of this since while we are in Iraq, we also have to be mindful of the Shitte population in there, (we will be needed to take out Iranian assets which would be hard if the Iraqi populous is in an uproar) so we only take a role from a "defending Iraq" standpoint. In that function we take out anything that flees east from Syria.
3. Iran "comes to the defense" of Syria. There is only one way to get there and that is through Iraq. At this point Iran an in essense invaded Iraq and we can still take the defensive role in the overall senerio by stopping Iran and decapitating their millitary effectiveness.
This also prevents us from fighting on two major fronts in Iraq. It puts us in the strategic catbirds seat. Of course this is just my personal assessment of a best case senerio if this is going to go hot for the entire region and I'm not a military strategist.
I'm OK with that.