Greetings and salutations.
Assume that the Germans manage to avoid provoking the US into joining the war.
The later, bigger, and better Michael offensive still fails (the British reserves that were in the UK at the time OTL are in place, and the German troops can't help stopping to do some looting after years of deprivation) and the lines stablize a bit further west. 1918-1919 is a bad winter for Germany, and although they manage to do further damage to Italy, to the point where only French and British forces manage to keep all of N. Italy from falling to the Germans and the Italians essentially refuse to take part in any further offensive actions, there is no corresponding success in the west: indeed, the British forces, as they learn how to use their increasingly numerous tanks, manage to make slow progress through the spring and summer (joined by the French once they see progress is being made): by fall, Allied troops are on German soil, although as the Germans learn how to best kill tanks progress has been slowed. To the SE, increased German support is required to simply keep AH from collapsing.
The US continues to support the UK financially (US lenders are so deep in the hole now that only energetic looting of Germany will ever bail them out), and the Ukrainians continue to raise objections to giving away their food to German citizens. When yet another "potato winter" looms, Germans finally crack, violent protest breaks out, red flags are raised in a dozen cities, and the defense of the west crumbles. Austria-Hungary, meanwhile, essentially implodes. By Christmas it's all over but the shouting, and the new government hastily moves to arrive at an armistice with the Allies before they can march into Berlin.
Given this sort of victory, what do you think is the _likeliest_ peace the victorious allies will impose on the Germans? How will they deal with the Poles? The Soviets? (Which have had a sortof year's reprieve: still pressed hard in 1919, the Allies have little to spare for the Whites, and they in any event note that the Soviets aren't actually doing anything to help the Germans, aside from not-fighting-them). The Ottomans/Turks? (Still dug into their trenches in eastern Anatolia in late 1919).
Bruce