And even more so with a shortage of fuel in later stages of the invasion. However, could you elaborate somewhat on other reasons why it might fail plz?
Better readiness of conscripts in France and Belgium?
That's part of it, but not all. They were also still working up their formatioms after calling up the reserves. The French also had substantial amounts of equipment on the way or just arrived from the USA, and large amounts of production just coming out of the factories or being fixed.