So let´s see,
the Germans simply wouldn´t launch an offensive against the Maginot line, if the makers of Operation Sea Lion didn´t even consider it, then you also know it isn´t because they where gutless wretches.
So what does Germany do in 1939? Will the extended Maginot line make Hitler more carefull in 1939, knowing France cannot be vanquished?
In the case things are little changed compared to IOTL, what does Germany do in August-October 1939? (butterfly effect resultin in either slower or faster pace of events)
Knowing Germany may face a two front war, Hitler decide to mobilise from day 1, instead of day +1170 of the war.
This greater mobilization goes into the construction of a massive reinforced line along the Franco-German border. When would that reinforcement be scheduled for completion? I mean, when did the Germans estimate that the French would launch an all-out assault against the west line?
The Phony War continues up to summer of 1941, the Anglo-French have constructed a massive force to breakthrough the west wall, helas for them the west wall haven´t been static in the last 18 or even 9 months. Their tactics remaines awfull, they fail to breakthrough the west wall and suffer massive casualties in the process, sustained massive casualties against fortified zones will not stand´with their public opinions. If the French governement insist on a even worst version of the trench wars, soldiers will mutinie, the people of France will rise up and overthrow it!
Big question is, what happen with the Soviet-Union?
At some point, even with less movement warfare, the Ploesti oilfields won´t be enough to sustain the German war effor, especially if it is fully mobilised.
Does Germany launch an offensive in summer 1940 against the Soviet-Union, hoping the Soviet regime will collapse in a few weeks? Or does Hitler cancel the operation until the Anglo-French launch and fail their offensive?