There's going to end up being a realistic limit on fps as well. You're getting in to the territory of slow motion there, and slow motion is generally used to show one short thing as 240fps is four times longer than standard 60fps.
Other thing with higher frame rates is the amount of light you need. Getting above that demands more light to get a better exposure.
Traaditonally cartoons ran at 24fps and that was smooth enough, higher fps removes any perceived flicker, but I challenge the average person to honestly say they can tell the difference between 50 and 60fps. I've not seen 120fps yet, and I don't think it would be anywhere near the difference that 60fps is from 30fps. On to battery and storage, you're in to writingh 4x the amount of data in the same time period, which then requires more power.
It's back to the general needs. If you NEED high quality high fps footage then you're in to buying a Phantom, but theyre larger cameras with phenomenal storage and a big battery, the battery is 3x the size of a GoPro on the Phantom Flex.
GoPro are great cameras, but they're not true broadcast cameras, they're action cameras deaigned to be body worn for POV shots. It's not a television camera. It doesn't cost £40k either. The whole optics thing is another debate too.
Horses for courses.