I can only say what the actual numbers show. Germany was done for in 1919, whether the Americans entered the war or not. Her, Germany's, manpower was exhausted, her economy' especially the agricultural sector was in a state of total collapse. No more cohorts to levee existed. The people were starving because the farms had no production. So all the Americans did, was end it a year earlier, and a year gentler. It could and would have been a lot worse in any realistic AU imagining. The British and the French had just enough left in them to finish the job. You better start with a negotiated peace no later than 1916 before the real damage is done.
I agree with the facts you stated, mostly, but, still, I disagree. Yes the people were starving, there was practically no agriculture, etc. but Russia had left the war and millions more troops were freed up for the Western Front. Until they ran into the Americans at Château Thierry, they were barreling through the Brotish and French and would have taken Paris if it weren't for those meddling Americans!
Based on the research in John Mosier's Myth of the Great War, the Germans suffered much lower casualties (based on actual casualty figures instead of British propaganda) than the British and French and evolved superior tactics on both the offense and the defense. The basic stormtooper tactics were being worked out as early as 1915-16 by generals like Von Mundra. The French (especially Petain) were starting to figure this out, but the British were still largely in the dark. Plus, the B-L treaty gave Germany access to large resources in the east that would have come into play eventually. No Americans, no Allied victory. Maybe a draw, but certainly a peace that would have left the Empire intact.
Think a bit further - a proud, intact Heer returns to smash revolts like the Spartakists and the Nazis throughout Germany (imagine Hitler and his cronies being hung in 1923 after his attempt is smashed by ironically the crack List regiment). A Heer that would be the bulwark against Communism (provided the Soviet Union would have even developed as a major strategic threat or even survived without the Ukraine and Baku. A Germany where a genius like Rathenau isn't gunned down by some right-wing kook, but survives to lead the rebuilding of the post-war economy.