Possibly, depends how smart the software is and I think*** a big part of their routing suggestion is based on previous user routing, journey times and volume, plus instantaneous data (i.e users are currently and suddenly taking 30 minutes to traverse a journey segment that typically only takes 3 min means there must be an obstruction). A knock on effect of this is that if multiple users diverted via footpath shortcuts while using Google navigation (Don't forget, Google harvest ALL this data and process it mercilessly) then this might become built into future routing suggestions, kind of like Strava heatmap data, which will take no notice of the legality of journeys but simply highlights popular routing?
*** could be completely wrong here but I reckon this is part of how they do it.