Iranian presence in Lebanon is overrated, and mostly hyped by people (e.g. Al Qaeda, Hezbollah, various other hardliners, etc.) who want a wider war.
Yes, Iran will let Israel smash Hezbollah.
In case you haven't noticed, Iran and Syria aren't rushing to Hezbollah's defense in Lebanon. Nor will they.
Just as they haven't in other Israeli invasions (e.g. 1997).
You can fall for the hype, or you can learn from history. I'm simply telling you what is and what will happen. In advance. Step by step.
Oh well there are lots of things I don't understand about the Arab Parallel Universe.