The Subsite
Reddit, Facebook, Twitter, etc. are essentially platforms for making websites. The goal of next generation social media should be to realize this property: Rather than make a subreddit, or Facebook page, or Twitter account, I should make a website. Call such a website a subsite. The subsite owner retains control over content. They are able to add features to make their users happy. Rather than stagnating, the platform is able to evolve. Rather than concentrating power in the hands of a few, power returns to the people. Next generation social media should be merely a set of tools for connecting subsites together.
I envision a few different such tools. One is essentially a login system, but more than that: it is zero click account creation. I have an account on this website that I just visited for the first time 3 seconds ago. This is different from social login: with social login, existing social media controls the account. With a zero click account, the subsite owner controls the account.
The next tool is a hub that collects all of a users subsites in one place. Because it merely collects data from elsewhere, if the user doesn't like the way their current hub works, they can pick a different one with no penalty. Just as above the subsite owner retained control, here the user retains control.
This is only the beginning. I love the innovation that technology companies have brought to the world, but when they become too large, they become sclerotic and controlling. It's time to change that.