This item seems unaddressed in your document:
Risk that the counterparty is also a huge individual miner and can steal some funds (in case of receiver) or even all the funds (in case of UTXO owner/initial sender)
In general, I think it’s worth comparing this to LN-Symmetry (eltoo). In that protocol, the worst case for an honest party is that they’ll lose transaction fees putting the latest state onchain,[1] which can be a very small percentage of a high-value channel.
In your proposal, an honest party will lose a significant fraction of their funds in order to penalize a dishonest party.
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For the receiver Bob, that means he may only accept such a UTXO from Alice under a discount compared to cheaper-to-enforce mechanisms, e.g. Alice_BTC will be worth less than regular onchain BTC.
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For the spender Alice, that means she may only be interested in offering such a UTXO if she can earn a risk premium on it above the market rate for other less-risky investments.
If either or both of those values significantly diverge from 0%, it’s unlikely that there will be a market match.
LN works well because the expected loss to an honest party is small, so neither side is requesting a premium or a discount. I’m not sure a system with a high risk of loss can work as well, unless everyone can be absolutely sure that the game theory nearly perfectly predicts that no one will defect from the cooperative strategy.
Assuming mining remains uncensored. If there’s enough collusion between miners to censor transactions, then a miner colluding with an malicious counterparty can confirm an old state. ↩︎