I was only just shown this post today. Thanks very much for the time and thought you put into this post, it's clear you're very knowledgeable on the subject matter.
One thing I really appreciate about the mechanism you describe is that you’re using non-coercive free-market forces (pay to voluntary state-producers) to influence the underlying consensus structure. It's very important to me that we use voluntary, non-coercive, credibly neutral solutions. I have also spent a lot of time considering similar solutions (I helped write the fractally whitepaper, and you can also see the EPN Whitepaper for similar ideas).
But I have some reservations with your solutions described here.
It may be unnecessary
I’m not convinced that the separation of transaction ordering and state computation is necessary for a community to be fully autonomous. I understand that this separation has some advantages, perhaps it makes the process of migration between chains easier. But in fact it’s already possible for DAOs to migrate between chains, so long as the DAO doesn’t hold any assets it’s not sovereign over. Especially if you consider running one's own chain a possible solution, which I think we should, then you can even simply replay all transactions from chain A on chain B to arrive at the same state (More complicated in EOSIO, because you would need to turn off TAPOS for the replay).
It’s technologically complex
This solution requires special APIs and state computation infrastructure to be run by existing block producers, which is socially and technologically difficult. You also require a community of validators to ensure the state producers remain honest. Given this technological complexity, any community willing to undertake it may as well just run their own blockchain.
It’s game-theoretically tricky
State producer pay as described is not proportional to the state-producer’s stake in the underlying chain. If you choose which BPs to reward by rank (as proposed) or another objective metric, it incentivizes a sybil attack.
Final thoughts
I think most of the worry about violations of autonomy do not come from the fear that the underlying network validators will censor or abuse your community, but rather that the community itself will depend on state outside of the control of their own contracts, and thereby prevent their ability to resolve internal disputes by forking state. I think ~90% autonomy can be achieved simply by ensuring that a community uses it's own token, rather than using the underlying network token, and by eliminating any dependencies on off-chain assets. The final 10% autonomy can then be gained once the community earns enough revenue to afford running its own blockchain infrastructure.