@tosh While we do intend to end support for the legacy test interface in the future, this will happen in a gradual and well-planned manner. Once the new pm.* interface has been made functionally complete as compared to its legacy counterpart, we’ll gradually make the messaging around the removal of legacy support more prevalent. For instance, the new pm.* interface does not have a postman.setNextRequest equivalent just yet (see Improve postman.setNextRequest())
One way to do this would be to start displaying warnings whenever the legacy interface is being used.