More and more flights (maybe 25% of my flights lately) have internet that is fast enough for and allows streaming video. This trend will continue I'm sure. Obviously downloads are still really beneficial but it's becoming less and less of an issue on flights.
Annoying, but if you're a first-gen user paying $3500 for the device, you probably either have Apple's TV/movies offering or don't care much about paying for it for your flight.
No downloads without a native app, which could affect the whole "using it on a plane" thing people keep mentioning.