The German right consisted of 5 armies the 1st through 5th. The French left was 3 armies - 3rd, 4th, 5th, plus the BEF. Assuming Moltke refuses his right wing then either Joffre advances into the Ardennes on his own or he does not. If he does not, then German forces go east and crush the Russian invasion.
If he does, then 3rd and 4th armies would have advanced in the general direction of Trier via the Ardennes and Luxembourg while French 5th and BEF provided flank protection. In this scenario, the status of the Belgian army would be unknown, as Germany will not have invaded Belgium while France has. The French far left would be advancing along the southern bank of the Meuse with the Belgian army concentrated to the north of it on the axis Brussels-Antwerp. Presumably French reserve divisions would have to be deployed to 'watch' the Belgians.
Once the French center reached the vicinity of Trier, the refused German right (still in its concentrations zones in Germany) would unleash the Schlieffen Plan. The French 5th army would be hit and defeated by German 1st and 2nd, and thrown back across the Ardennes in a meeting engagement. The German right then seeks to pocket the French 3rd and 4th by driving southwest to link up with the Metz-Thionville fortress line via Luxembourg. Since the French are now with the Ardennes at their backs,their LOC for retreat are curtailed.