When it comes to contracts I think a more interesting idea is a limited formal expression of them and thus automatic production and evaluation/translation/summaries (would require a formal spec for each domain with very limited options), not a Turing complete expression of them which as you say leaves too many holes. Also tying all of this to a currency and payments makes zero sense and just expands the attack surface massively. Just fixing contract law with automated checks of contracts would be a huge opportunity/challenge.