Again sorry, but that is a comment by an unreliable narator, that also sounds very French. Also destined could Imo mean that the French planned to go into Belgium... but until now we have not seen them do it in a major way. Add that a naval bombardment of the coast or a raid could still count towards Belgium being a battleground.Author's fiat - Belgium will be fought over.
So in the end, we do not know how the TL will resolve and as of right now, I personaly see the Germans in a much better position then in OTL. Even with the uncaracteristicaly defensive French in the beginning Germany is still better of then OTL as they control very important resource areas that OTL were important in keeping the French going and the better position regarding the Channel.
One thing that is still shrouded is the Eastern Front and that could scupper up the German position, but without the fighting in Belgium and thus the availability of troops OTL bound there, I think that the course should not change overly much. As the systemic problems of the Russians are still the same as OTL and Germany should have more resources available to deal with them.