He did mention changing the monetization scheme used by twitter from being ad-based to being subscription based. I've heard this idea floated around for awhile and my favourite version is something along the lines of requiring a monthly payment once you reach a specific size of followers/audience. The idea being that today, twitter is being used by corporations/individuals as essentially free marketing.

Although not guaranteed to solve the issue of "free speech", I would be interested to see the results of a social media service that is not designed to maximize engagement to drive the most ad dollars.