re: How far are we from partial game tickets?

There are ideas out there suggesting as people leave a game early, they can hand in their ticket stub and then the ballpark/ arena could allow people that have gotten on a waiting list to take that seat.....much like a restaurant works. I'm sure it would be young people/ poor people waiting but at least the place wouldn't be empty. Related to this idea is if a seat is empty after a certain amount of time after the game starts, the venue could re-sale that seat. If you are running late you could call in or go online to hold your seat. But so many seats are bought by corporations/ companies that go Unused its obscene.