Next month, two seminal image-sharing communities, FFFFOUND! and MLKSHK, will close their doors within a week of each other. There's a profound difference in how they're doing it as noted by someone who's previously sold off a community.
This is a great little piece comparing and contrasting how to relatively similar online communities and social silos are shutting down their services. One is going a much better route than the other and providing export tools and archive ability to preserve the years of work and effort.
For more about social media sites, communities, and online silos that have shut down before, see site-deaths on the Indieweb wiki.