Computers don't operate in isolation. Timescales of centuries requires us to rethink networks; how do you:
Edsu is an identity, storage, and communications protocol that addresses these challenges. It is capable enough to create replacement applications for social media, chat, and messaging, while being "in the time capsule" along with the other Forever Computer Project technology, so it can be depended upon to not become a source of incompatibility in the far future.
Edsu is federated, which means that if every provider goes away, you can always act as your own.
Its design pushes functionality into the application (which is running on a Forever Computer), not an emphemeral server in the cloud. Its explicit dependancy graph means that complete archival of both an application and whatever data you access with it can be made - with no missing links when it is revived in a different era.
Its authentication, identity, and fine-grained capabilities mechanisms mean that a lot of the functionality traditionally performed by an operating system isn't necessary, allowing for sophisticated, networked apps to run "on the metal", with only statically-linked library support.
The extreme simplicity of its storage format and communications protocol, and its decentralized architecture (i.e. no performance-critical centralized bottlenecks) means that a complete re-implementation of an Edsu server on future technology (or on a Forever Computer acting as a server) will always be a modest task.