So, the Germans turn east.
1. Britain is going to get involved, but it needs another excuse to excite people enough. Some kind of incident among the North Sea fishing vessels should do it. They will join, but it might take 3 months or so. The Germans can use those months to import vital raw materials, food and get raiders out to raid French shipping (which can also raid British shipping one they enter the war).
2. France will execure Plan XVII and will be stopped in Alsace-Lorraine.
3. The Russians will suffer badly and most of their pre-war army will be destroyed. The Austrians will do much better (but still not well) and will not suffer the devastating defeats they suffered until Spring 1915 OTL. This leaves their army in a much, much, much better shape once they start getting modern equipment (especially Skoda artillery) in early 1915.
4. I assume the German Mediterrenean squaron will go to Istanbul as OTL and will force the Ottomans into the war as OTL. With the British not yet in the war, the Ottomans can concentrate their resources in the Caucasus. They will not get anywhere, but the Russians will have less troops to commit here and the Ottomans will be stronger, so the Ottomans will jsut be stopped, not reversed and suffer devastating casualties. The Ottoman army will be slightly better off.
5. The Austrians will not lose Galizia and Przemysl, leaving their army much better of, but above all their economy much, much better off. Galizia produced a large amount of food, and when they lost it OTL they lost most of their pre-war locomotives and rolling stock, which had been used to bring the troops to the front. Galizia also produced a large part of the oil of Europe at the time.
6. Russia will probably not surrender in 1914 and not in 1915 either. Serbia is probably taken out as OTL (the Austrians were too weak to do it themselves when having a majority of their forces on the Eastern Front) with Serbia joining the war. Russia is mobilising more troops and bringing them to a front that is further back along their supply lines. However, without the victories in Galizia to add to their prestige, and more devastating defeats, their army is weaker.
7. With Russia weaker and Austria much stronger, Italy will probably remain neutral and profit from being a hole in the now established British blockade. This means Germany and especially Austria can get goods and food from Italy and pay with coal and oil (which they will be able to get there since the Austrian transport is in much, much better shape).
8. Something akin to Gallipoli probably still happens, since the British and the French only have a short front to fight along. They might also attempt to land in Albania to offer a route of retreat to the Serbs, but that would anger Italy. Parts of the Serb army makes it to Albania, but is unable to fight.
9. If the Austrians look strong and the Russians weak, Romania might actually be bribed to join the Central Powers. Getting Moldavia and Odessa and perhaps some small border changes in Transylvania as well as being promised sharing the Russian Black Sea navy with the Ottomans could be enough. They join early 1916, which is a death sentence to Russia. Revolutions spread and Russia bows out of the war Summer 1916. It is possible that Sweden joins the war early 1916 too, attacking Russian Finland.
10. Before the Russians bow out, the Entente is probably desperate enough to actually violate Belgian neutrality. By early 1916, the British have a sizable army in France, and the French, not having much of their industry, iron and coal mines destroyed and not suffering the same casualties, are much stronger. British and French troops sweep into Belgium to "protect" it. Only parts of the Belgian army resists, eventually joining with German troops coming from the east. The front stops in central Belgium.
11. When Russia bows out, the British abandon Gallipoli - there's no reason to hold it. They go to Greece as per OTL, but with the Central Powers much more successful, they are unable to get Venizelos to support them. They face littel resistance, but no support either.
12. The Germans set up client states in the Baltic countries and Congress Poland becomes an Austrian puppet Kingdom with an Habsburg on the throne. Romania gets Odessa and Moldavia, the Ottomans gain Kars and puppets a Circassian Kingdom in the Caucasus. The Romanians and Ottomans split the Russian Black Sea fleet. Sweden gains the Åland islands and substantial influence in the newly created Kingdom of Finland (which otherwise is a German puppet). Germany gets most of the Russian Baltic Sea fleet, but Sweden gains some too.
13. The Austrians move south, forcing the Entente forces in Albania into Greece, while the Bulgarians advance and surround the Salonika bridgehead. This is now Austria and Bulgaria's only front, while the Ottomans have to hold Iraq and Palestine against British attacks. They do this fairly well, though, since their army has suffered less fighting the Russians and the Germans are able to provide more supplies and weapons (since they can get raw materials through Italy and they don't need to supply Austria as much at all).
14. The Germans now move a majority of their forces, supported by some of the best Austrian forces (they are unable to support much troops in Albania and thus have spare troops), to the western front for a grand offensive. The offensive is a moderate success - the casualties are STAGGERING on both sides, the lines do not move that much. However, the Austrians and Germans are making overtures to the Italians, the Austrians can provide more troops if they do not need to guard the Italian border, the Germans are moving more forces from the Eastern Front, since their puppet states, Sweden, Congress Poland and Romania can hold what they hold as a guarantee for war reparations (and seizing harvests and raw materials) and keeping the reds at bay. The Germans are a bit ambivalent on the civil war in Russia - they do not allow Lenin to go to Russia, and it looks like the whites are going to win, but it will be a hard fight. They don't want Russia to re-surge, at the same time, they don't want a power that have not signed the peace treaty to assume power.
15. The combined Ottoman-Romanian navy (which are stronger with Russian ships now entering service) is making a presence felt in the Mediterrenean, as is the Austrian navy - they are incapable of taking control, but they are storng enough to warrant a British presence, as the French need help - they cannot hold the Mediterrenean themselves without Italian help. This means the British are a bit weaker than OTL in the North Sea. Germany is a bit stronger, not needing to hold down the Baltic (they can leave that to the Swedes as the Russians lack a navy in the Baltic Sea) and having a few Russian ships. And equilent to Skagerrack happens, with somewhat more casualties for the British, but not enough to break the blockage. The Germans are bound to try again.
16. In this situation, I am inclined to think the Entente would ask for terms if they cannot see the US entering on their side anytime soon. The Germans will probably not have made overtures to Mexico and will not have started unrestricted submarine warfare since their situation is far better than OTL, which might mean that the US is less inclined to come and help.
The Great War was in many ways also a product of governments failing to stick to a united diplomatic policy.