Complex problem for sure. Opened main/service doors would need to be closed and then re-armed before the slides could be deployed. The exits just aft of the trailing edge are permanently armed emergency exits only. It may be that a combination of usable exits and the air bridge offers the best solution. In my airline, crew are trained to open an exit and evacuate if they consider the situation is life threatening.
It all goes to prove that any real emergency is unlikely to be text-book.