For real. What is plausible and what is maintainable should be very high on the list.

When a social media site runs on ads, it will inevitably begin to shift to being advertiser friendly. When it's a paid site, it will struggle to get users. Might be worth investigating a Patreon or Reddit type funding, where paid users get benefits, awards that can be handed out, message amplification and ad blocking, but where anyone can create an account.

It might be useful to also integrate the Brave browser format where the users get credit for viewing ads that can be traded to other people or spent in an online store for fabulous toys and prizes.

The reason I'm saying all of this is that what an alternative to Twitter needs in order to serve the people is a funding method that does not rely on stocks and shareholders, but that also has a method to manage invasive business practice while remaining profitable. The system should be technically owned by the people and therefore be a place that people would want to gather together without the worry of money having to change hands in order to use it or have a painless experience.

Aside from that, it should offer frictionless open APIs to developers (<- very useful for getting people invested in the platform), it should have a topic filter (for instance, I am not interested in Sports at all, so being able to filter out Sports related topics would vastly improve the experience for me), and in addition to that, there should be a free-for-all town-hall section that removes any filter other than your personal blocklist and does not allow ad/business accounts to post but could have non-targeted generic ad billboards.

That should help minimize echo chambers or at least provide an easy way to step out of your echo chambers without abandoning them.

People need a place to speak and think and breathe without ads and agendas being shoved on them, where ordinary people can speak freely to other people and be evaluated on the quality of their thoughts and posts and not on artificial amplification of weaponized memes and polarizing agendas crafted to serve the financial desires of the wealthy elite.

Also, you can't trust one person (even yourself) to hold the line against the riches and power of the world, you can't trust even an organization founded on the purest of intentions (like Mozilla) to be able to resist both the peaceful and hostile machinations of such people should you reach market saturation.

The company charter would need to be built on principals designed to prevent the consolidation of power and control over the platform into the hands of the few, with some system in place to enable the people to eject other people from the platform entirely. I'm not sure what that would be, maybe every 3 months the top 10-1000 accounts get put to a vote (from verified human account users) and if there are enough votes then those accounts get memorialized and the user has to take 3 months off from the platform and then create a new account.

Sorry for the brain dump, but these are things that might have either improved Twitter or prevented it from becoming a billionaire's plaything and are therefore things I would like to see in whatever rises from its Phoenix Ashes.