Really depends on how they race it (and before). Groenewegen got dropped after 8 km in the TTT on a section of - what - 2, 3%? Yes, he was probably suffering more from his fall then than now, but today and yesterday are both >200 km stages. Steels has said it's possible to shed riders there, I believe him. It will require a very dedicated effort though, and after the côte as well, to keep dropped riders from making it back.