As long as it is financially viable, I'd say. Right now, the crown still brings tourists, sells tabloids, books & souvenirs, so in balance it is net positive. But once that is gone, I think it will be just a masquerade. Technically there is still a king of Yugoslavija somewhere (Karadjordjević), but who is he? Sure, he has some inheritance, and he does get to be invited to royal funerals, but that's about it.