It would be interesting to see what effect this would have had on the United States. The significant German-American population of the Midwest could continue to speak German, and perhaps in isolated towns the language could survive to this day. After the Franco-Prussian War, Germany was seen in a positive light by Americans, with Bismarck, North Dakota being named after the German Chancellor in 1873. Also, without the need to resort to sinking merchant ships, and not invading Belgium, public opinion wouldn't turn so harshly against the Germans.
Though there were Anglophiles in America, if Britain were distracted by an uprising or Civil War in Ireland this could turn some public opinion in America against Britain (at least in heavily Irish American areas). There was admiration for France in some circles too, however it seems that there would be little sympathy for Russia, with over 90% of immigrants from the Russian Empire being Jews, Poles and to a lesser extent Finns.
If Italy and Sweden join the Central powers you now have the significant Italian, Swedish and Finnish populations in the U.S. looking favorably to the Central Powers. Also, the large Jewish community in the U.S. was composed mostly of recent arrivals fleeing the Russian Empire, though they might not be pro-Central Powers they certainly wouldn't be backing the Entente.
With a harsh peace treaty, France would have been forced to pay heavy reparations to the Central Powers. Stripped of most of its industrial regions and colonial empire, perhaps the United States would have agreed to purchase France's American territories, giving the Americans more islands in the Caribbean, French Guiana and the strategic islands of Saint-Pierre and Miquelon.
Another country that was an ally in WWI that would probably salivate at the opportunity to add more territory is Japan. In OTL they declared war on Germany to annex the Pacific Islands. However, once things start going badly for Russia, they can join the fray and annex the Northern Half of Sakhalin. I can also see them going after the sparsely population regions of Outer Manchuria and the Kamchatka Peninsula. This could be interesting as Japan would be turning its interests Northward and finally have the "living space" it desires. This area is also rich in minerals especially gold and could lead to Japan soon afterward annexing all of Manchuria with Germany's blessing.
Also, I can see the Japanese assisting the Germans in attacking French Indochina, however I have a feeling the Germans wanted this territory for themselves. The Japanese could assist German expeditionary forces in taking New Caledonia and French Polynesia, however, I believe the Germans would probably wait to annex these after the peace so as not to alarm the nearby British Dominions.
Portugal too could probably join the Central Powers if Spain does. The only reason being they fear Spanish invasion and would think its better to be on their side so that they aren't attacked. Though they wouldn't add much to the cause, the Germans could use the Cape Verde Islands and Portuguese Guinea as a springboard to invade and capture Dakar. The Portuguese could probably get the Germans to agree to respect the territorial integrity of Portugal's colonial empire since now Germany's imperial appetite would be satisfied at the expense of France and Russia and this would be considered a victory for the Portuguese Government. Also, economic concessions would probably be granted to the Portuguese and perhaps they can acquire a small amount of territory in the form of the Cassamance Region of Senegal that had been ceded by Portugal to France in 1888 and where Portuguese cultural influence was strong.
In the end, without the British and Japanese against them, most of Germany's colonies remain safe, with the exception being Togoland (which the French probably quickly overrun in 1914). However, Germany will be able to mount expeditionary expeditions in Africa and Asia with the help of its allies, and probably begin taking over French colonies. German East Africa would serve as a springboard for an invasion of the Comoros, Madagascar and Reunion, Kamerun for French Equatorial Africa. Finally, I can envision joint Spanish-German invasion of French Morocco and Algeria to aid the Italians to meet up with the Italians in Libya.