This is a question that, truly, only Orthodox can answer. Most secularists, intellectuals, Protestants, and left-leaning individuals would say the Reformation was a wonderful event for Western Civilization. On other hand other, traditional Catholics would say it was a hindrance to missionary development and the cause of unnecessary wars. Of course, they may concede that the Counter-Reformation was needed for "modernizing" Catholicism and justifying the growth of the modern education system. We have to remember that the Renaissance brought us the Reformation which brought us the Enlightenment which brought us to the Modern Era, secularism, and later the Post-Modern Era. There's a strong correlation between the Rise of Protestantism, the fracturing of the Christianity, and the decline of social values. As Orthodox Christians, we are firmly on the sidelines on this issue as Orthodox countries were largely independent of these events until the modern era as Peter the Great wanted to make Russian more 'European' and the yoke of the Ottoman Empire fell.
For the sake of argument, let's continue with the notion that Reformation never happened. Luther became a lawyer and remained a pious Catholic (he and conservative Lutherans would say he always remained a pious Catholic). First, this would mean that the Counter-Reformation would never have happened. Catholic historians would challenge this, but it was the Reformation and the rise of intellectualism that greatly propelled the Counter-Reformation to occur, which largely addressed 1. Clerical abuses and 2. Laity education. It's also hard to determine if wars could have been avoided, since immediately before the Reformation, the Hundred Years War had ended, between two Catholic nations, and the wars of the 17th century were largely secular in nature. Likewise, it was largely Protestantism that founded the United States because of religious freedom - a notion largely unheard of in Western Europe for nearly a 1,000 years.
Catholic missionary work has been on the decline since the late 19th century. As such, Protestantism has stepped up to the plate in filling Rome's shoes. While we can focus on doctrinal differences, even the most traditional Orthodox can agree that it is more efficacious for non-Christians to hear the Gospel from Protestants than not at all. The counter-point to this is that Protestants are largely encroaching on traditional Catholic or Orthodox lands, and, instead of working with local bishops, are aggressively working to "save souls" despite their already Christian adherence.
It's hard to say at this point what could have happened if the Reformation never occurred since it's been nearly 500 years. It's a worthwhile debate nonetheless.
