With current DVDs you can store the film as 24fps with 3:2 pulldown on playback (at least for NTSC). So with the next generation, they should have made ALL films stored at 24fps, and they play back at a certain speed depending on your player settings. eg. if you are in PAL-land, it plays it back 4% faster and adjusts the pitch on-the-fly (or have a separate audio track). If you are in NTSC-land, it performs 3:2 pulldown. It could possibly do SECAM stuff too but I forget what that would involve.
The resolution would be stored at PAL high-definition res, and could be scaled-down on playback for NTSC.
This would make truly universal discs that wouldn't need localising for different territories. And then you would start to see hybrid TVs with the better PAL resolution (and 24fps progressive) being sold in the US for high-end home theatres. Perhaps eventually we would all have TVs with the same formats.