The entirety of your fiat and Bitcoin holdings is stored in an account in your name with Prime Trust LLC, a Nevada chartered licensed and regulated Trust Company. 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.
As always, we encourage you to withdraw your Bitcoin often to a secure wallet whose keys you control.