As the Arab Spring (and I guess people are now calling it the "Arab winter") taught us, anything is possible. People, parties, and states can do anything.
So I have no idea what will happen across the Shia crescent if Israel, the US, or a coalition including Britian, decides that surgical airstrikes against Iran's nuclear facilities are a good idea. Hell, maybe they're not even sure . . . But one thing is:
This week, Secretary General, of Hezbollah, Hassan Nasrallah, said this:
“The [US] must understand that war on Iran and Syria will not remain [restricted] in these two countries but will spread to other countries in the region. We are not issuing any threats but this is the reality."
“The era of weakness and [submission] to the US or Israel is over. We have entered the era of victories."
I'd count Hezbollah in. And as Nasrallah also pointed out in his speech, Hezbollah's rocket arsenal has increased dramatically since 2006.
Middle East could be in for a massive bummer.