It may appear to be a dumb move, but say a service account has purchased both the PS3 and the PS4 versions of ARR, but has only purchased the PS3 version of Heavensward. Will that Heavensward purchase be able to convert to the PS4 version when Stormblood is released and the PS3 support is removed?
This is not my situation. It's just a question that occurred to me. I tend to think it's not something that will affect very many people.