I think we would see all of the *carriers merging into one airline before there would ever be a unified FFP... For programs like aeroplan which is going further and further away from a FFP to more a strange/expensive reward system with FF component. Of course regulations would stop any sort of unified worldwide carrier although the at the speed Lufthansa is buying airlines who knows!? I do add that I would be one of the first to sign up for a unified FFP!

Happy Travels!