Your last 2 ideas could be merged. The blockchain shouldn't carry photo and video links in my opinion. But what could happen is that a photo sharing service could accept STEEM in order to host the images/video. A feature would be built in, that they agree to take 5% of your post's payout. This way if you go viral, their 5% goes viral too. Put that with all the steemit posts, and it would be a very lucrative business for those "steemit partners" that wanted to support the system.