I just don't see ABT doing a 3 hour work. There is musician and stage hand overtime to consider. My husband was a stage manager on broadway shows and time was always of the essence. Aside from that this is a work people bring their kids to - it it lasts for 3 hours it better be very magical.
ABT has been using 7:30 start times during the week nights, so that doesn't seem too terrible for a ballet to get out around 10:30. Most Broadway shows let out around then. And I believe a 10:30 curtain would satisfy the unions also.
Opening night for ABT, the Ushers noted how nice it was to get out at a decent hour. Met Operas can last 3.5 hours.