It is all up in the air really. If they can't get your attention they will have to write it off. Seen it a few times at all the casinos. Maybe the policy have changed and will not be as liberal and forgiving as before.
At Foxwoods high limits area I saw a guy walked off the table and didn't pay the $600 commission. Dealer contacted the supervisor, then supervisor made a phone call upstairs. Then just wrote it off like nothing ever happened. Maybe the casino will contact the player if he used his player's card.
At the Wynn the guy had a $50 commission and walked off. They went after the guy chasing him down and made sure he paid. Well I know at the Wynn/Encore they make sure you don't owe them anything before you walk off with your chips. It is the only casino I know of where they ask to check your player's card and asks you if you have any markers before they exchange your chips.