I think you're looking at this more from a video gamer's standpoint than an RPG player's standpoint.
The whole concept of "break combat" makes me think, "Run away until the music changes." or "Get the baddies to the edge of your minimap to break aggro."
Rather than looking at combat as something that can be turned on and off like a switch, look at it realistically, with consideration to the situation and participants.
Is the battle on foot, in vehicles, or in space? How badly do the pursuers want them?
In most cases, the party will need to shake the pursuers in some way, leaving them behind in a way that the pursuers can't hope to follow. A jump to hyperspace is the obvious answer in space, and other options may involve stealth (a cloaking device, diving into a nebula, etc.), becoming a needle in a haystack (blending into traffic patterns, heading into an asteroid field, or getting a head start and putting down on a planet when they're out of sensor contact), or simply outrunning, if they've got the sublight speed advantage over every pursuer (literally point yourself at open space, shields double rear, and floor it...you'll increase your lead every round, leading, eventually, to a jump).
Similar options, but without hyperspace also apply to vehicles, with added options of pulling a maneuver around an obstacle that the pursuers can't match (refer to the swoop chase inside the weather control station from Han Solo's Revenge), ditching the vehicle and slipping away on foot...or making it to a ship and blasting off.
As characters, some of the vehicle options still apply, as well as breaking off pursuit by physical means (literally blocking the path you've taken), deceptive means (get lost in the crowd), legal means (think in terms of escaping the pursuers' jurisdiction, or making it to a friendly embassy), or some other means that effectively means the pursuer stops any sort of active, direct pursuit (their pursuit may well devolve into a more generalized search effort, but the dynamics of that situation are significantly different enough from a chase to not confuse the two).
For a good example, look at the recent Rebels story arc where they meet up with Rex. They're in the walker and Kallus locates them, triggering a chase. They head into the sandstorm to lose them, and while Kallus has a pretty good idea of where to look, his tactics clearly change from chase to search because he's lost contact with his target. It's not until Rex's walker fires a weapon that contact is re-established and the chase begins anew. Without the storm, there's no reason to believe that any distance on that wide open desert plain would have been enough to break off the chase unless the lead got to the point that they were putting the planet's mass between them. After all, if the pursuer can see the target, they can still pursue.
Thank you. And yes i was/am looking at this in more of a video game point of view than a table top point of view. I am a big console RPG player and have more recently started playing table top RPG's so i am still trying to switch my mindset in that aspect. I really appreciate your point of view on this so if you dont mind i am going to explain the situation and want to know your opinion on how you would have handled it.
(first off the reason they got into this mess was partly my fault)
We were playing dead in the water and the PC's got through act 1 fine but that's were everything went wrong. They took argued for awhile on what they should do first, get their equipment or head to life support. so after a few minutes of them arguing i started a dice counter on the table to let them know that they needed to hurry up and make a decision. They opted to get their gear but wanted to explore the floor they were on first. because of the previous narrative and the explanation of the connecting rooms they got an idea of what was where on that floor. Again they were taking a long time looking through each room top to bottom so i enacted one of the time events this time telling them that the air was getting a little stuffy. They split up to search faster one team going to search the bridge the other to the escape pods. since the narrative had said the bridge was taken over and that wasn't the direction the story was supposed to go i tried to dissuade the players from going inside by telling them that there was a lot of droids in there including the Nemesis. They retreated back to the other player that had been checking the pods for any emergency breathing devices. When the players that had seen the bridge met up with the player checking out the pods they exchanged what they had found out. However this is where things went bad. The player that had been checking the pods had the Combat Superiority duty and decided that since the leader of the droids was probably the biggest and baddest of the bunch, she decided that she was going to storm in there and fight him. It didnt matter that i had put 5 other droids in there. So long fight short the players took a beating, killed all but the Nemesis (which only took 1 damage in the whole fight BTW) and an astromech. The fight took so long that the ship was minutes away from being sucked into the black hole and they wanted to retreat. Not knowing how to do that i told them each to make athletics checks to try and turn and run and if successful they got out of the room if not they continued to get shot at. Once they were all out they shot the door and sealed the Nemesis in but not before the astromech got through. They got to the pods and escaped jettisoned, making an piloting check to see if they escaped the black holes gravitational pull.
I get what you are saying about not ever realistically "breaking combat" but when does it go from turn based 2 maneuver to free maneuver. if that never happens then they would never get far enough away to escape.