Hi James,
Is your Basic SKU Public IP address associated with Azure Cloud Services (extended support)? If yes, it is unaffected by the retirement. Please see excerpt from the notice:
If you have any Basic SKU public IP addresses deployed in Azure Cloud Services (extended support), those deployments won't be affected by this retirement and you don't need to take any action for them.
Please click Accept Answer and upvote if the above was helpful.
Thanks.
-TP