I don’t think most people need to adopt this on their cameras for it to work. My perspective here is that journalistic sources that want to be trusted could employ this system. Along with signing the media and the blockchain, a system would need to be built to simply show the change log and history of a photo from the source. These journalism websites could just link out to it to demonstrate their veracity.
Once that’s adopted by the NYTs, WSJs, BBCs of the world, I’m hoping there would be critical mass to pressure more and more journalistic sources to adopt this standard. Eventually, any credible journalism would be on this technology and any outlet that doesn’t use this would be viewed with a grain of salt.
I agree though that a number of developments would have to happen to make this a reality. I would think that a partnership between NYT and Apple or Nikon could kickstart it though.