And what if Iran falls? No more proxies, at least from Iran. I'm aware the masses in Iran are not fond of their theocracy, and Iran poked Israel (a bad idea...a lot of their air defenses have since been destroyed). If it falls, and there is no more support for the proxies, will they wither on the vine?

That really depends on what comes next after Iran "falls." It's hard to guess what that would look like. It's pretty unlikely that the theocratic regime would be replaced by a pluralistic open democratic government that seeks to re-align itself with the Western powers. Normally the most likely successor to a regime falling is that you get a military dictatorship - but the Iranian military is fully controlled by the theocracy, and Israel just killed Soleimani - so that doesn't seem in the cards. But if it were, a military dictatorship is still probably going to remain aligned with Syria and China and Russia, and is going to play the "great game" of regional politics and jostling for power, and will probably still find a policy of containment against Israel and the West to be a viable strategy.

If Iran descends into more of a failed state, then they're probably not pursuing any coherent foreign policy. But failed states are often a great source of resources for regional terror organizations.