As a guess, German forces reach Paris in early September/late August as without British reinforcements the French are unable to hold. Much of the French Army near the German border begins to withdraw in an attempt both to avoid encirclement and help defend the capital but this only exacerbates an already terrible situation. Italy sees the fall of Paris coming and declares war in exchange for everything east of the Rhone river save Lyon, Avignon, and Marseilles with a 10-mile radius around the first two and a land connection from the latter to the rest of France, Tunisia, Corsica, Kerguelen, Djibouti, and maybe French Guiana. Austrian troops are then rerouted almost entirely to the Russian front as are large numbers of German troops.
With a cease-fire in late 1915/early 1916 and a 'Treaty of Chernowitz' or equivalent, Germany still incorporates Luxembourg directly, makes a satellite out of Belgium and Poland, almost certainly takes Belfort and at least Murelle et Mosse (if not the Meuse and Vosges to complete a takeover of Lorraine). Until the ores of the Pyrennes or its colonies can be exploted this leaves France in a precarious position as she has few metal resources left - a hybrid Green/Accion Francais movement where recycling is imperative for national security (and the environment!) could emerge as a result.
Russia is still 'beaten' with a much less harsh peace in 1916 with the loss of Poland, Georgia, Armenia, Azerbaijan, perhaps Lithuania, perhaps the western Ukraine, and *maybe* guarantees for Finland and the Alash/Cossacks though I doubt either get independence. Far fewer people die, Ottomans really win as do the Bulgarians and Germans, and more likely than not the AH devolves into either a federation of a loose ecomonic pact with maybe some sort of federal army and common currency. Berlin becomes the new superpower and another war will happen but without the memory of such a terrible conflict the next one is likely far worse.