There seems to be a certain... inertia, to the way historic events fold out. Allow me to try to formulate this. Any part of history is the product of interactions between ruling classes and their populace. Ruling classes influence their populace and each other, but their are certain times where the populace influence the ruling classes.
A question I often ask myself is " What if it had been Churchill instead of Chamberlain?" Would Churchill have tried to find appeasement with the Nazi regime? There is no true way of knowing this, but it is my belief that the call for appeasement was largely supported by the UK populace. As a true political animal, Churchill would at least have considered the same course of action Chamberlain actually took.
When it comes to matters of military nature I often ask myself how the Renard R.38 would have faired during the opening stages of the war. It might have been a good airplane, but could it have made a difference against the vast number of modern German aircraft invading the Belgian skies? I don't believe so, as the Zulus, Mongols, Soviets and such have shown numbers in themselves are a weapon.
The interbellum is filled with moments that seem as if they are keystones to the futher evolution into the history we know, our final product. But I don't believe they are all that important, as these moments in themselves are again a product of various actions and inactions, various interactions between rulers on all levels of society and the people they rule.
So... What if the Maginot line hadn't been there? I don't believe there is any doubt that the French would have amassed a substantial amount of defensive forces along the French / German border. It would still have been a very risky undertaking to vanquish these forces in a conventional head on way, and risky undertakings are something any military leader wishes to avoid as much as possible. Therefore the logical step would be to circumvent these forces... through Belgium? The option of least resistance.
