POD: Moltke realizes that Paris is out of reach, stops short of the Marne, sets up defenses and starting the race to the sea earlier. Somme river and Amiens, Abbeville are reached/taken.
http://upload.wikimedia.org/wikipedia/commons/5/56/Western_front_1914.jpg
Edit: Let me flesh this out a bit. Moltke recognizes the increasing exhaustion the campaign is taking on his armies as they press hard for the Marne. Supplies are low and the armies are out marching resupply. He worries that going after Paris will overstretch his weakened forces and they will bog down on the forts, while suffering a counter on the exposed flank to British or French reinforcements. His sleepless nights finally get to him and on August 31st orders the following marching orders: First, all cavalry divisions are to detact from their army groups and head to the channel. The fifth, fourth, and third armies are to dig in on the Aisne and Vest rivers, while the fifth army contributes some formations to cutting of Verdun. The first and second armies are to head west to the Channel and seize Ameins and Abbeville while setting up on the Somme. Each army is to detact a corps which then will occupy the Channel cities Boulogne, Calais, and Dunkirk, while being supported by the various cavalry divisions.
These orders are followed, which enables the advancing armies to seize the coast by September 5th. However, further south, the orders have a different effect. The Allied forces see that the German armies have stopped and split. There are now German troops setting up on the Somme and Aisne rivers, which significantly extends the amount of ground each army must cover. The time seems ripe to counter attack while the Germans are resting before their final push. Joffre readies his battered armies to attack and cajoules the Brits to help, despite their panic at being cut off from the channel ports. The Allied armies move in for the battle of the Aisne on september 3rd. Ultimately the battle proves fruitless as the entrenched Germans are not shifted, despite casualties to both sides. The Brits become panicked when it is realized that the Germans were stopping to set up permanent lines and cover the troops seizing the Channel ports. This delays reinforcements as panicked politicians hold back troops to counter the 'expected' German invasion, which never materializes. The Allies then proceed for the next several weeks to break the German lines and liberate some valuable territory, but the entrenched enemy proves too strong to budge and the French artillery proves too weak to dig him out. German troops are stopped at Verdun and settle down into trenches. Ultimately a major reorganization takes place on both sides, as the various besieged forts in the German rear fall and the line solidifies near the front. Troops are able to be freed up and sent into the reserve for other use or rest, while the units in France are replenished with Landwehr and newly trained recruits. The end of the beginning and the calming down in the West allows for some machinists to be returned to work and train replacements while less vital men fill their places in uniform. In the East the fighting continues and intensifies as units are transferred eastward, including several that head south to prop up the bloodied Austro-Hungarians.
In the Allied camp several things has happened. First, the openning campaign proves to be the end for Joffre, as he has let the Germans seize the major industrial regions of the north without so much as a success in the field. The BEF stays somewhat smaller for 1914-early 1915 as more troops are held in Britain. The professional army is essentially wiped out in the various counter attacks lauched to penetrate the German lines. The Front stretches from Compeigne to Montdidier and the Somme, while further south Verdun is still threatened. The French have the bulk of the line and are less able to launch attacks as much of their industry is now in German hands. Nevertheless, the attacks to liberate France still occur well into 1915, but they produce little of value, save for securing Verdun. The Russians are in a bad way, as more Germans are present, especially supporting the Austrians. 1915 shapes up to be a difficult year for the Allies.
This scenario means the Uboots are farther forward, Britain commits for forces at home, as fears of invasion hold them back for defense, the German lines are shorter, which means more troops, earlier for the east front. More of France's industry is in Germany's hands and perhaps the High Seas Fleet has extra basing options to harrass Britain. It also means greater mining of the channel, which complicates traffic for supply. Overall much better for the Central Powers and means Verdun becomes a focal point earlier, as the Germans now have extra troops for pinching it off. But the allies have shorter lines too, which means it takes some pressure off France and allows for a greater reserve. The Allies are unlikely to have greater success attacking that OTL, as the ground is essentially the same, but if the Kinder Mord doesn't happen, then Germany has more troops and is better off in the deal.
Is this possible and what does this mean for the course of the war into 1915? Maybe Falkenhayn wins out over Ludendorff and gets to hold on to the chief of staff position?