I don't think it's anything to worry about - the whole retirement thing seems to happen pretty slowly. I'm not sure about publications, but I've seen retiring Prof.s stop taking on new students, stop teaching - all over a period of 2-3 years. They won't be abandoning you, and I don't think their enthusiasm wanes any either. I'd much rather have a retirement age supervisor with a lifetime of experience than an unsettled younger supervisor.