Its funny some people neglect butterflies - America declared war in Spring 1917 - and some think a year or so is unaffected...
If the US is not declaring war on Germany the there must have happened something in Germany - And that is Germany does no longer believe that it can starve Britain (NO USW)
Even if the US gives loans to Britain and France (and Russia) after collateral has dried up (likely sometime 1917) this will likely decline if not stop AFTER Russia drops out (likely to happen as it happened OTL when the US DID join). Britain and France must du what A-H and Germany did - finance the war domestically - , but thats probably no game changer.
The French mutinies were ended with the promise of no offensives until the Amercans arrived - OK what to give them instead? At one point soooner or later the French will have to resume offensive actions.
The Russians - I assume Kerensky will want to fight on as OTL, so the likelyhood of the October revolution is also likely. OTL the Soviets stalled the peace negotiations - I assume mostly due to the hope of World revolution, but also because in hoping that the Entente wins before (Soviet) Russia must give up too much. You can also assume that Russia WILL actually make peace a little bit faster.
Germany - assuming that they will not be as active as OTL (instead of a big spring offensive make that some smaller offensives with limited goals). But this leaves some units free to fight at other fronts: support the Turks - the British offensives will not be that sucessful (at least not more than OTL) - German good troops and more supplies will probably prove invaluable. Even IF Britain iss more sucesful, the supply lines grow longer while the Germano-Turkish ones will be shorter - guess the lines will go back and forth for some time. Support A-H vs Italy and Bulgaria on the Balkans...
Basically Germany must not act in the west and spend its last strength in the spring offensive, while France and UK in a much weaker position (no US troops) wil likely have to attack (Germany is holding large parts of France and Belgium while theres only little of Germany held by France.
In addition if Italy is out (by mid/late 1918 latest) A-H can free men (Slavs probably first) to return home and produce and grow... and stil have the more loyal and efficient Austrian and Hungarian troops free to support Germany (And Bulgaria and Turkey)
Self determination of people - well it was Wilsons idea - imagine that the idea will have less impact on A-H if America is still out
Colonial troops - why did the Brits not mobilize India earlier - well they could have from 1914 on, but the did not because they feared that meant to lose India in the long run... This fear might not go away - after all India is worth more to them than A-L...
With the US out of the equation the situation of the CPs is going to improve while that of the Entente is worsening in comparison. As the CPs were in quite a good situation early 1917 - even improvening a bit during the year, its hard to imagine that they can't take the war into 1919 - well I assume that both sides will be exhausted by then (morally) and they will likely make a somewhat white peace with both sides get and lose something (to prepare the stage for act two

)
BUt is a White peace (west) a white peace?
I think not - as said the french and Brits have taken much money from they US they will have to repay (Without reparations) - wile the CPs have finaced the war domestically - the CPs will recover much faster than the Entente...