The entirety of your fiat and Bitcoin holdings is stored in an account in your name with Prime Trust LLC, a charted and licensed and regulated Trust company in the United States. In the unlikely event that Swan Bitcoin ends operations, you still have legal control of funds stored within Prime Trust. You can continue to custody your Bitcoin with Prime Trust, or you can request disbursement by emailing Prime Trust directly.
You can also refer to Prime Trust's related FAQ here.
As always, we strongly encourage that you withdraw Bitcoin to your own custody. If you are not familiar with self custody, please refer to our wallets FAQ and related blog post for more information.