To bring up the issue of the Ottoman Empire again, Germany by the period considered had EXTENSIVE economic ties to the Ottomans, and would have reacted badly to any Russian attempts at aggression in their direction. This may have been enough to rupture the alliance, depending on what actions Russia took, which basically means that the OTL WWI power structure would have asserted itself...a few years later.
This would have two consequenses. The Schleiffen Plan would probably not have been adopted as in OTL (at least, not in its original form), because Germany and Russia would be allied and Germany wouldn't have needed a short war in the west so as to bring its armies to bear in the east during the time that the plan would have been considered. This means that German war planning, once Russia broke off the alliance, would be rather more haphazard and would be rather more focused on Russia, not least because the Germans would be very aware of their earstwhile ally's capabilities. The second consequense is that there wouldn't have been any appreciable staff contact between France and Russia, leading to a much weaker alliance between them.
Speculating further, we might see a static defense against a Lorraine offensive, possibly with the Germans falling back to the Rhine, while the bulk of the German army defeats the Russians by 1916 and turns to the west. With Belgium unmolested, England would have no cause to enter the war, and France, isolated by the defeat of Russia, would fall sometime in 1918. Then, of course, there's the social and political turmoil suffered by France and Russia after the war to consider...