During the July crisis, John Morley asked his cabinet colleagues the simple question "Have you ever considered what will happen if the Russians win?"
A delightful question for us so let's assume the Russians win- The fighting in August-September goes pretty much OTL with a deep German thrust being checked and the Germans falling back.
However, in the East everything goes Russia's way. Rennemkampf punches through the cavalry screen and falls on the rear of the 8th army turning Tannenburg into a crushing Russian victory Meanwhile, in the south Conrad moves even deeper into the trap and the Russian 3rd and 8th are vigorous in closing the circle. Only a scattering of Austrian units get out
Essentially, the Austro-Germans have nothing left in the East and the road to Vienna and Berlin are open for the Russians
What sort of peace terms are likely to be imposed on Germany and Austria and more importantly, what would the military and diplomtic position of Britain and France be?