Would it be possible Germany's initial offensive in Western Europe 1940 to fail but Germany's succeeds at a later date in overrunning Western Europe.
How much of a delay could be possible
What would be the impact if the fall of France was delayed
Entirely possible. The whole plan depended on difficult successes at critical bottlenecks. A section of AA MGs on top of Eben-Emael commanded by a gutsy NCO might, alone, means a delay of two days in the whole operation, possibly a week - and that alone would have catastrophic cascading effects.
The German armed forces remain better than the opposition overall, and it's very likely they still continue to achieve a series of victories - a series of
limited, smaller victories. But the tempo of the operations goes from one that the French comamnd system couldn't handle, to one that it was built for, and the German victories come at a price, paid especially by the fast but fragile and few German armored divisions.
As to the impact, it depends on how long the delay lasts. If, as it is possible, France does fall anyway in 1940, but, say, in August or September, then the whole timeline of the war goes astray. Italy probably does not enter the war. The Luftwaffe is not bled white in the Battle of Britain. The Soviets continue to have unexplainable organizational problems in supplying oil and other raw materials to the Germans. The Romanians and Hungarians and other minor powers are much less impressed with the Heer, which is now sizably smaller due to heavy losses, and more on a WW1.5 footing, and needs to keep a few third-rate divisions guarding the Italian border. In short, a pretty significant impact.
OTOH, if France has not fallen by September 1940, then bad weather arrives, and the delay would go up to the next year - a WWI scenario and an even more significant impact. So significant that Hitler may have a deadly accident while cleaning his pistol, followed by a German proposal for negotiations.