Upgrading strategies for B-ISDN systems are investigated and refined by studying the evolution of telephone and broadcasting services. The study suggests that the penetration of B- ISDN could require more than a century. The evolution of B-ISDN for the first thirty years, which is divided into three phases of a period of ten years each, is predicted. Upgrading strategies from phase to phase are investigated both for B-ISDN services and subscriber networks. A typical example of optimizing such strategies is studied to show a possibility of providing attractive services (such as super HDTV with a 2000 lines resolution) at a reasonable cost (such as 2000 dollars per subscriber).