I think that there are many similarities between today's world and the world prior/leading up to World Wars I & II. With tensions rising between countries in the Middle East, the rise of ISIS, and growing tension between Russia and the West, alliances are once again surfacing and interfering with global interactions.
Keep in mind, this is not a question of whether or not it will/will not happen, but rather if you think the conditions are similar enough that we could be/are beginning to head down that road again.
If you look at either instance of WW2 or WW1, you will see one thing in common. 1st) It took something of immense political and social impact to move the engines of war into full speed. In WW1, the assassination of Arch Duke Franz Ferdinand and his wife who were shot at point blank by Austrian revolutionaries. In WW2, we have the escalation of Nazi discrimination and prosecution by race, not to mention the unjust invasion of Poland. 2nd) Nobody in those times had ICBM's (aka nukes) that could literally knock the entire earth two inches off its axis if all that exist were to be fired. That may seem insignificant, but that much of a shift would make the Sahara a frozen wasteland, and Siberia and immense desert. We as a race have become a little bit more weary than you'd expect of the power we possess, and the threats you see now days about launching nuclear weapons are either greatly exaggerated or the countries that claim so actually have no real threat in the field of nuclear weapons (ie. North Korea and how their "missile of destruction" crashed into the ocean, and the project blew up in their faces). The big moves you see in nuclear tech are really a massive game of chess. moving assets into different positions solely for the purpose of intimidation and testing the other nations fortitude. There are few ways to compare the world of then to the world of now. In today's world it has really become a game of political adversaries, not brute strength. It would take a major event to set in motion another WW, WW3.