I recently accidently deleted a content type from the content type hub which had been published and consumed by more than 50 site collections. This action left content type in the site collections orphaned from the hub. It took only one click to delete the content type and there was no warning.
Not only should a warning be provided and acknowledge before you delete, the content type should also be recoverable either through a recycle bin type experience or via Powershell/PNP.
In addition, if a new content type is published through the content type hub with the same name as a content type already used in a site collection, there should be an option to merge the two content types and reinstate the publishing relationship.