Consider the situation where two clients have an open channel with some funds deposited. Now the client devices both crash in a way such that their data is not recoverable (i.e., the devices are destroyed), while the private key wallets still survive. In this case, there is currently no possibility for any of the clients to recover the deposited funds, as they need to provide a mutually signed channel state for that. Hence, the channel funds are stuck forever.

It could be desirable to extend the contracts so that a client can always register withdrawal of its initially deposited funds if it still has access to the private key corresponding to the channel account.