dont worry, things will change over time:

- passengers standby for earlier flight
- passengers making changes to their travel plans
- passengers/airline making upgrades
- passengers not showing up
- airline releasing travel agent booked/unused inventories back to the pool
- equipment changes etc etc....

last time when i did HKG-ORD, the entire Y was full.... thought i will be in trouble.... ended up getting an E+ seat with an empty middle.