Barbarian incursion
Ostrogoths
Visigoths
Franks
Rebels
Gepids
Huns
etc....
Austria Hungary would have been crushed on 3 sides and the Eastern Front (in Russia) would have seen a stalemate similar to the western front. If America joined the war it would already be too late. Most likely Germany would run out of materials if the amount needed were just as bad on the east than on the west. However the Ottomans might not even make too much of a difference. The Ottomans got nearly all their armaments from Germany and it is unlikely that Russia or Britain would be able to supply them in the numbers that Germany did. So it is also possible for the central powers to win but only if the Ottomans are just as ineffective as in our timeline. The real factor that will win the war is whether or not America joins the fight. If the war isn't won with a quick victory Germany would most likely see similar progress on all fronts (although slower, mostly on eastern). Germany would eventually get to Paris unless the allies get America to join the war because without the US they would quickly run out of manpower and supplies. And if the western front fell and Russia hasn't fallen into bolshevik revolution by now it would take the full force of Germany (Italy wouldn't be a big problem central powers defended their border). After that it would most likely fall to revolution after huge losses from Central Power offensives. The ottomans after the fall of Russia would surrender. But all of this given the chance that America decides not to join the war. And with Germany at war with the Ottomans, they might take steps to avoid American Intervention.
I believe it's called checks and balances.
