The article sketches a number of likely developments in scholarly digital editions and other scholarly digital resources. They will be composites of independent and distributed components, containing multiple media, and subject to permanent change. These trends seriously increase the as yet unsolved problems of sustainability that the digital edition presents. The article argues that sustainability should be based on a service-oriented architecture, based on separation of data and functionality, and a cloud environment, characterized by redundant implementation of data and service components. To guide and monitor these processes will be a new challenge for the academic library.