Hi Hacko1,
From past experience with this when I have lost an old card and casinos are refusing to pay anything to any other deposit method until my withdrawal amount reaches my net deposit amount; your old debit card no matter even if it is expired or cancelled remains linked and connected to your bank account. This means that even if refunds or payments are processed to an old card, you will still receive the funds in the same account that your new card is linked to. This has been the case with me with both RBS and Barclays so I am assuming that the majority if not all banks will have the same procedure in place.
I suppose this may vary depending on the casino and bank so if you have any doubts I would hit up Live Chat and give your bank a quick call to clarify.