Air carrier pilot reported a hydraulic system failure during cruise.

Narrative

During cruise flt at FL390 we we got a notification that one of our hydraulic system had lost the hydraulic fluid after running the non-normal flight attendants were notified of the problems we had; also that I did not expect it to change unless we had additional systems degrade. They were given the time to landing; and were notified about the fact that we were gonna have to be towed in. We were entering ZZZ airspace from ZZZZ and [requested priority handling] based on the fact that we knew that we were down to alternate braking and also no ability to steer the aircraft off the runway after landing. Air Traffic Control was told of all the issues we were gonna have; but also that we expected it to be a normal landing with no forced deplaning however we were gonna be unable to get off the runway without tow. We were then given a vector to ZZZ and requested to land on Runway XX left; which were the longest runway available in ZZZ. Just outside the initial approach fix we started emergency extension of the gear as suggested and before that we notified ATC that we were gonna slow down. Once the gear was down successfully extended we tracked inbound at 180 knots until touchdown. After a normal landing and normal braking distance with one reverser available we came to complete stop and set the parking brake. We then started to shut down the engines and notify the Tower that we were ready to be towed in. I then notified the passengers that we had lost our ability to steer on the ground in route and we're waiting for tow vehicles to come and bring us into the gate and requested that they remain seated and keep them seatbelts on. I also notified the passengers that when you stop on the runway as a precaution; emergency vehicles would come out and take a look at the plane to make sure that nothing that we were unaware of was wrong with our plane.Once the emergency vehicles were done with their inspection the move team moved up and hooked up to the aircraft and brought us to gate XX.No further incident of any kind on the way in. During this incident; no emergency authority was taken by me; and even though we lost one braking system; we still had two more options; including reversers; so I expected a normal landing and; did not expect any emergency deplaning of the aircraft unless we had further system degradation. For safety reasons; I elected not to try to move the aircraft off the runway using the brakes since that would've hampered the accessibility from emergency vehicles that may or may not want to check the aircraft. Other than the hydraulic leak; no additional damage to aircraft passengers or crew was recorded by me.