WHen the battery gets that low, you'll have some issues that many consider a safety concern. Given that, I doubt it will happen. For example, the car will incrementally start to shut down functions, and as the charge gets lower, you'll lose performance, which many have complained about if they're on the freeway, and suddenly, the car won't go over say 40mph anymore. If the level gets much lower, and is left in a cold environment, you can get some damage to the batteries if it sits long enough. Given that the estimate is not perfect, it could drop considerably to a point where you're stuck.
2011 535i x-drive GT, 2014 i3 BEV