I have to wonder if the next flashpoint for a resurgent European War by 1934 or 1944 might be ITTL, a resurgent and industrializing Young Turk Ottoman Empire, which is really an Empire of Islam. Give the Ottomans time to reconsolidate their Empire, particularly by defeating the Rashidi and Sauidis in Arabia and retaking Yemen (which went independent in 1913) unless the British prevent it. And then trying to get back Al Hasa and Al Qatif, where much of the Persian Gulf's oil is from Great Britain's clutches.
It is easy to see how a newly industrialising Sultan or President could embark on the same irredentist path that IOTL, Hitler did. Because the British and the French are sitting on Muslim territory and as Christians (who by their lights should be dhimmi) are ruling over Muslims, To Muslims, that is as much of an outrage as Czechs ruling Germans in the Sudetenland.
It can easily start with an Ottoman takeover of a weaker Iran (and oppression of the Shia Muslims there). Then Afghanistan. Then an Ottoman Empire, which by this time (1940s) as the industrial might that Nazi Germany did IOTL starts making ultimata over British control of Egypt, then wanting Libya back from the Italians and Tunisia and Algeria back from the French--Morocco and West and Equatorial Africa too. And Turkestan from Russia and the KMT. And Muslim parts of British India.
It can be hard for us to get our heads around, but this is because the British (perhaps wisely) acted to foster local Arab nationalism and thereby divide the Islamic world, preventing it from progressing. If this dosen't happen, between the oil wealth and other mineral resources (Saudi Arabia and Iran IOTL have plenty, not to mention Afghanistan) the West can face an Islam that industrialised at the same rate as Wilhelmian Germany or even faster. That could be the real next threat to world peace assuming the British and Russians and French do stay out of war with Germany.