German victory is pretty much assured in this scenario. Unrestricted submarine warfare will begin in earnest and the British will be starved to the peace table. If Britain goes, the French Army may mutiny in the trenches, forcing France to exit the war out of sheer panic. Without a Western Front to worry about, Germany can turn its full attention to the East. Without a blockade of the German coast, Germany won't be starved for goods. America may not sell to them, but there are other potential sellers out there.
Without a Western Front to worry about, I'm not entirely sure whether or not the Germans would unleash Lenin upon the Russians. Whether or not the Russians would continue the war with the French and British bowing out is up in the air.
Some ideas for a peace treaty would be:
-Poland (comprised of the land taken by the Germans in the 1915 offensive) would be carved out of Russian territory. Germany would get the islands off the coast of Estonia and Finnish independence is a possibility, but if the Germans want to create an independent Ukraine, asking for Finland to be free just may be too much.
-Luxembourg would be wiped off the map as it would be absorbed into Germany. Belgium would maintain its independence, but would be a demilitarized zone. The only forces permitted in Belgium would be militia units. Belgian fortifications would have to be dismantled. Germany may also get the Congo from Belgium.
-Ireland would probably be an issue forced by Germany, assuming they manage to get a revolution off the ground while they find time to starve Britain into submission. The entire island would become free of British rule.
-France may have a hard time getting off light. A Versailles style treaty may be implemented against France. However, since Germany wouldn't be able to occupy all of France's empire (considering Britain, which had only been forced to the peace table, wouldn't allow this), they'd be able to keep most of their colonies. North Africa would become a German mandate. Considering France will be able to keep a good majority of her empire, it's quite possible that they will be able to keep a navy, although a small one due to treaty limitations. Whether Germany tries to claim all of Lorraine is worth a coin toss. This may be an idea for a plebiscite area. Depending on which side Italy joins, Savoy and Nice may become plebiscite areas as well. Also depending on Italy is the fate of Monaco. If Italy maintained her treaty obligations, Monaco would become an Italian protectorate. However, since Italy would probably still go the historic route, I say it becomes a German protectorate. Also, the final indignity will be that France will have to sign off all claims to Alsace-Lorraine.
-Italy, quite possibly having gone the historic route, will be the easiest to punish. The Dodecanese Islands and Libya will be returned to the Ottoman Empire. If Germany took Djibouti from France, Germany may grab Eritrea and Italian Somaliland for good measure. I doubt if Austria-Hungary would be able to assimilate any territory taken from the Italians, so Italy may get off very light in Europe.
-Britain is worth mentioning simply because they were forced to the peace table. Britain may be forced to make the Suez Canal an international zone. The Ottoman Empire may also get Cyprus back. Granting the independence of Ireland is a given.
-Romania would probably experience no territorial losses, simply because Austria-Hungary would be unable to assimilate the nation into its empire. However, Romania may receive a puppet king in the form of a German prince.
-Serbia would lose Macedonia to Bulgaria and would also have to pay a fine to the Habsburg family.
-Japan may be allowed to keep the colonies she took from Germany. That's up to a coin toss.
-Australia and New Zealand will have to return the German colonies they seized in the Pacific. The British could also force this issue to placate the Germans for the loss of territory to the Japanese.
-Egypt may or may not become independent. If Egypt becomes independent, then they may attempt to nationalize the Suez Canal. However, one way of keeping this potential crisis from fomenting would be to give the Sinai to the Ottoman Empire, allowing one of the Central Powers to keep a close eye on the Suez. Also, if Egypt is not in Britain's orbit, the idea of Anglo-Egyptian Sudan will be butterflied out. Sudan will just be another British colony.
-Canada will get off light simply because they are in the Western Hemisphere. The idea of an independent Quebec will not suit the Germans simply because they don't want to free a Francophone nation.
Well, that's all I was able to come up with.