A Thirty Years' War in the Muslim World?

It's often said, in an attempt to explain if not excuse Muslim violence in the 20th and 21st centuries, that Islam is a younger religion than Christianity and Judaism and thus in an earlier stage of development. We're only in the 15th century of Muslim century, which dates from the hijra of the Prophet Muhammad from Mecca to Medina. Using the history of Christianity in Europe as a model, Islam should be on the brink of a "Reformation" period of change, turmoil and war, from which the religion as a whole should emerge less warlike and more tolerant of individual and regional differences. It's sometimes said that nothing short of an equivalent to the Thirty Years' War of Christianity's 17th century, an ultimate showdown between Catholics and Protestants, will drive home to Muslims the folly of imposing religion or denominational dominance by force. Seen in this light, it looks like that war is coming ahead of schedule. Geopolitically speaking there's been a cold war between Iran and Saudi Arabia for some time now. The Syrian civil war has been a proxy battlefield for these two powers, with Iran, a Shiite state, supporting Syria's Alawite ruler and the Saudis supporting a largely Sunni insurgency, with the self-styled Islamic State (aka the Daesh) as the joker in the deck. Now the Saudis have intervened with air power in Yemen, where a Shiite insurgency has forced the Sunni President out of the capital, with "al-Qaeda in the Arabian Peninsula" as the wild card. The Shiite Houthis have at least the moral support of Iran, where the government should be credited with some broadmindedness by regional standards. Neither the Alawites of Syria nor the Zaydi Houthis of Yemen are of the same Shiite denomination, roughly speaking, of the Iranian majority, yet Iran, seeing itself as the champion of Shiites in general, doesn't hold that against them, while Saudi Arabia has been the wellspring of increased intolerance among Sunnis. However, Iraq complicates any scenario portraying the Shiites as the good guys, since their overcompensation at Sunni expense for oppression by the Sunni/secular Baath regime created more support for the Daesh than it deserves. Also, Iran's Islamic republicanism, with its theocratic veto over elected leaders, is no model for other Shiite countries, although as far as I know the Iranians aren't pushing it as a model for Yemen or other places. The overall problem in the regime seems to be a rule-or-ruin mentality that distrusts power sharing because each tribe or sect distrusts the others. The question for the future is whether the region can learn from other regions' histories of misfortune and avoid repeating them, or whether they can only learn that whatever they're fighting over isn't worth fighting over the hard way. The question for the U.S. and Russia is whether either country can resist a temptation to help "their" sides in the larger conflict. Russia has made common cause with Iran in Syria, but it's unclear whether Putin favors Shiism in general or has a particular stake in Yemen. Americans remain convinced that Iran is evil and its influence must be limited or eliminated, so the challenge for us is see things clearly in Yemen without the screen and buzz of Iranophobia. It really should be no other country's business -- not ours or Russia's, not Iran's or the Saudis' -- how Yemen settles its internal conflicts. But the djinni is already out of the bottle there, and all we can do is hope the stain doesn't spread too far.