It will run till everyone is out of the park. One time we were the last people out of HS. Had a late dinner reservation at 50’s Primetime, after we made the reservation they change the park hours to close before our reservation. I think it was closing at 8, but they moved it to 7, this was in 2020. They still allowed the reservation. We were basically escorted by cast members all the way to the busses. One would follow us for a short distance then another would follow. We started talking to the last CM and as we passed the Skyliner station she advised us that we were the last guest to leave HS. When we arrived at the busses there were about 15-20 waiting. How often does one have 15+ busses waiting for their party of 6 to go back to the hotel. Disney will not leave you stranded at a park if your staying on site.