What airline makes you pay for the seatback IFE system? Any low-cost carrier that would do something like that forgoes the system entirely in my experience.

Instead they're just going to lose out on WiFi fees.

The ones that you fly long distance with, like say from Europe to Australia.

The US3 (American, Delta, United) are moving towards BYOD even on long haul. Some foreign carriers are as well.

http://www.airliners.net/forum/viewtopic.php?t=1358839

I fly a lot (mostly in Asia) and I have never been on a flight that doesn't have them.

Last year, I flew United San Francisco to Seoul on a 747. None of the seats in economy class had a monitor in the seat. But they did have Wi-Fi service for the movies.