I'm not going to go into detail, as I don't think that we will have to go there, but breach of contract, unjust enrichment, and fraud would be a quick start.
I am sure by your question that you are not an attorney, but it is not that hard to collect on a judgment from an international arbitration as long as the debtor has assets somewhere outside its home country, since almost every country has signed treaties to enforce such judgments. Any Venezuelan assets anywhere (outside VZ which would of course not enforce) are subject to the collection effort.
Of course, it takes a long time to go through the process and this is not the route we would select. It would only be an action of last resort and I would not waste my time hanging on for the many years that it would take.
Bottom line, I don't really find this useless speculation helpful, just more handwringing from those that are ruled by fear.