There is no logistical reason why Israel should not prevail, but they can't do it from the air. Just like the U.S. has done in Iraq, it will require going door to door in southern Lebanon, routing out Hezbollah one by one.
Unfortunately, there would be lots of Israeli casulaties, just like we've suffered lots of casualties. Don't know if Israel has the stomach for it or if Lebanon would stand for it. But I'm convinced that's they only way Israel can win along this front.
When one is fighting for his/her very existence, having a "stomach for it" isn't an issue.