So, let's say that, while WWI still happens, the following changes are present beforehand by act of ROB:
1) The big one: Austria-Hungary is effectively history before the 19th century is out, disappearing around the 1890's at the latest. The Austrian half (Austria proper, Austrian lands claimed by Italy, Bohemia-Moravia, Sudetenland and Slovenia) is integrated into the Kaiserreich. Galicia-Lodomeria and Bukovina (either the northern part or all of it) is annexed by Russia. The rest is organized into a Kingdom of Hungary (pretty much the entire Hungarian half of Austria-Hungary, and later on Bosnia is added) that retains a Hapsburg monarch, but otherwise becomes little more than a German client state. Balkan states wanting a piece of Hungarian pie are forced to drop those claims by Berlin and St. Petersburg, who compensate them with Ottoman territory, but they're not entirely happy, and some are putting secret feelers to the Entente.
2) Around the same time period the Russians go to war against the Ottoman Empire and this time they don't stop at British and French threats, thanks to German backing. Constantinople and the surrounding areas become Russian exclaves, while the Ottomans become Russian puppets ruling over a rump Turkey detached of any territory the Russians, Bulgarians and Greeks deign to take. The Syrian-Lebanese and Iraqi-Transjordanian-Palestinian provinces are taken over by France and Britain respectively to keep the Russians out of the Arab lands. Russia and Britain squabble over influence in Persia/Iran, and this time there's no 1907 treaty.
3) Germany and Russia turn the Reinsurance Treaty into a proper alliance, effectively dashing French hopes for surrounding Germany. France gets some geopolitical compensation in the form of an Italy quitting its alliances with Germany in rage since Berlin didn't give it back its irredenta, but kept them for itself. At the same time, Britain is now 100% behind the French, and makes it absolutely clear. A firm Triple Entente now composed of France, Britain and Italy opposes the German-Russian-Balkan alliance by 1914.
4) Teddy Roosevelt manages to win the United States 1912 presidential election to become president for a third time. Roosevelt is even more pro-Entente than Wilson, and when the Lusitania is sunk in 1915, Teddy uses it as a casus-belli to declare war on Germany and its allies.
How does WWI turn out in such a scenario?
1) The big one: Austria-Hungary is effectively history before the 19th century is out, disappearing around the 1890's at the latest. The Austrian half (Austria proper, Austrian lands claimed by Italy, Bohemia-Moravia, Sudetenland and Slovenia) is integrated into the Kaiserreich. Galicia-Lodomeria and Bukovina (either the northern part or all of it) is annexed by Russia. The rest is organized into a Kingdom of Hungary (pretty much the entire Hungarian half of Austria-Hungary, and later on Bosnia is added) that retains a Hapsburg monarch, but otherwise becomes little more than a German client state. Balkan states wanting a piece of Hungarian pie are forced to drop those claims by Berlin and St. Petersburg, who compensate them with Ottoman territory, but they're not entirely happy, and some are putting secret feelers to the Entente.
2) Around the same time period the Russians go to war against the Ottoman Empire and this time they don't stop at British and French threats, thanks to German backing. Constantinople and the surrounding areas become Russian exclaves, while the Ottomans become Russian puppets ruling over a rump Turkey detached of any territory the Russians, Bulgarians and Greeks deign to take. The Syrian-Lebanese and Iraqi-Transjordanian-Palestinian provinces are taken over by France and Britain respectively to keep the Russians out of the Arab lands. Russia and Britain squabble over influence in Persia/Iran, and this time there's no 1907 treaty.
3) Germany and Russia turn the Reinsurance Treaty into a proper alliance, effectively dashing French hopes for surrounding Germany. France gets some geopolitical compensation in the form of an Italy quitting its alliances with Germany in rage since Berlin didn't give it back its irredenta, but kept them for itself. At the same time, Britain is now 100% behind the French, and makes it absolutely clear. A firm Triple Entente now composed of France, Britain and Italy opposes the German-Russian-Balkan alliance by 1914.
4) Teddy Roosevelt manages to win the United States 1912 presidential election to become president for a third time. Roosevelt is even more pro-Entente than Wilson, and when the Lusitania is sunk in 1915, Teddy uses it as a casus-belli to declare war on Germany and its allies.
How does WWI turn out in such a scenario?