Even had Kuhn claimed inability to pay, such a claim is not a recognized basis for the defense of impossibility.
"The continuation of existing market conditions and of the financial situation of the parties are ordinarily not such [basic] assumptions, so that mere market shifts or financial inability do not usually effect discharge under the rule stated in this Section."  R.2d Contracts 261, Comment b. 
     However, a party finding itself unable to pay an amount required by a contract, or unable to pay damages for breach of contract, might discharge or alter its obligation to pay under provisions of federal bankruptcy law. Consideration of the impact of a potential bankruptcy filing is thus an important part of the lawyer's service either to a client who owes money under a contract or as damages for breach of contract or to a client who is owed such money.  You may study federal bankruptcy law in an upper division law school course.