Whether the Central powers win or not, depends whether the US will join the war or stay out...
OK, I try to improvise a TL (only the things changed):
1914: Italy declares war on France, Britain and Russia. Italy starts offensive in Southern France, but is blocked in the French Alps.
1915: Since the Central powers don't have to fight on the Italian flank, they can overwhelm Serbia, Montenegro and Albania. Greece is indifferent; Britain wishes they would join them, but they don't dare to.
1916: Falkenhayn tries the Verdun strategy again. Romania joins Allies, but they are stopped. (Not sure whether Russia would become a republic.)
1917: Falkenhayn gives up, after one million Germans have fallen in the West and almost nothing has been achieved. Now it's Hindenburg's and Ludendorff's turn. They go east, as in OTL. Romania, Riga and the Baltic islands are conquered. Russia (being cut off from the Allies for two and a half years) asks for peace. This time, Germany is less desparate while Russia is more. They lose Poland, the Baltic states, Bessarabia and some areas at the Turkish border, but they keep Finland, the Ukraine, Byelorussia and the Transcaucasian republics. Serbia and Montenegro become Austrian, Albania goes to Italy, Southern Serbia and some other pieces to Bulgaria.
1918: As I said, it depends on the Yanks... if they didn't and don't join, the Central powers have quite a chance. Since all parties are quite tired, France and Britain might ask for peace, too. Let's say, they lose Savoyen, Nizza, Tunis, Malta, Djibouti and Somalia to Italy, Kuwait, Cyprus and Aden to Turkey and Longwy-Briey, Luxemburg, Zanzibar and the Congos to Germany which has to retreat from Belgium in return.
In the US should join, however, war can go on until '19...