You are right. This is why these things will not go anywhere. Ultimately they need some kind of "back up"... For example, the system we currently have flows like so: Nation state Military > Federal Police > Local Police > Physical Intimidation via face to face meeting. At every step, stop when lawyers and/or politicians get involved.
We already have well-established mechanisms to arbitrate these kind of disagreements, e.g. courts. Adding blockchains to the process just makes it more complicated for no gain.
Has no one addressed the basic need of a justice system with these crypto currencies?
Of course, this is entirely insufficient to do something like "put your corporation on the blockchain".
No reason an arbitration clause couldn't be included in the contract.
Ethereum contracts are turing complete. The payout function can be contingent on either the buyer or arbitrators releasing the funds. The arbitrators can be determined before hand or rely on an external contract that offers arbitration services. The possibilities are truly endless.
It might help if 'contracts' and payment amounts were small. In the Antifragile (book) sense: the fairness of any individual contract is fragile, rife with risk. However, in aggregation the system is antifragile (better than robust) as long as occasional bad deals are acceptable.
