Social media is still evolving, and I think there is definitely a market for new social media sites. I am 30, and use Facebook, and am told by younger people now that Facebook is old and what their parents use. I thought Facebook was the killer social media platform that everyone was on, but due to a number of reason people have migrated away - alot of them to Instagram.
This suggests that people are keen to keep up with the latest 'fad', and thus there is a market for future social media platforms to thrive. It seems that the 'life' of social media platforms is limited and newer ones keep coming along and outperforming the older ones
Yes, if they pay the users. Just imagine you will get money for your posts and activities, and for active followers. If any website offers good rewards for the subscribers, there is a chance to a big market.
Every social media website that we know of are famous because of their innovative and unique approach.
In its time Facebook was a new concept so it got huge and we started to think that no other site would make this much impact then LinkedIn came with a different approach and captured a reasonable market.
Steemit came up with another interesting idea ... that's to give the user incentives for being an active user/participant in form of cryptocurrency, and accompanying Steem Blockchain dApps are extending its reach and increasing the number of users.
There are other examples too, like twitter, telegram etc, which offer something different than others and people are kept attracting towards them.
So, it is possible for others too to come up with some "Out of the box" idea and capture the market.
Yes, because the potential number of people coming online is still counted in billions. The price of information technology is going down and the economy is growing in developing countries. There will be plenty of room for social media to grow in the coming years and perhaps decades.