Alas, there are some dangers where maximum damage could far surpass any liens. A good rule of thumb here is that if the risk is against a third party, and it cannot be liened or insured against, then PAs should not allow it to be taken. PAs that allow their customers to take such risks against non-PA parties would ruin their credit rating. One example of such a risk is building a nuclear plant for which no insurance company is willing to submit liability coverage. If a plant is safe, presumably one should be able to convince a good insurance company to cover its potential to damage others' property.
Smart liens are one element of smart contracts.
Smart contracts will replace, and even protect against, lawyers, politicians, and violent enforcement in many business and social interactions. They will also be used to design lucrative new free-market institutions. See my essay Smart Contracts for an introduction to smart contracts.