First, a little bit of background:
The goal of the Global Maritime Distress and Safety System (GMDSS) is to provide the communication support needed to implement search and rescue plans. The GMDSS is based upon a combination of satellite and terrestrial radio services, changing international distress communications from being primarily ship-to-ship based to ship-to-shore (Rescue Coordination Center) based. The GMDSS provides automatic distress alerting and locating in cases where a radio operator doesn't have time to send an SOS or MAYDAY call and requires ships to receive broadcasts of maritime safety information which could prevent a distress from happening in the first place.
Introducing a return link for Satellite-AIS would allow the satellite to communicate with the ship and also acknowledge a distress signal. As Satellite AIS constellations are low earth orbiting and not geostationary, there will always be a question of revisit but I believe that AIS, particularly Satellite AIS, will play a major role in the modernization of GMDSS. AIS is on every ship and once AIS is recognized as part of the GMDSS system, essentially every vessel will be a Search and Rescue vessel. Satellite AIS could then be used to increase the reporting rate on the new channels when a ship is in distress and, in the event that there are no other ships around, the satellite will be sure to receive the distress signal.