This isn't a visual history, this is a short article followed by a bunch of screenshots in chronological order (mostly from the Internet Archive) with no commentary beyond "According to X, this is approximately what the Delicious homepage looked like on Y."
Are we in a post-bookmark world?
Depends on what you use bookmarks for and what you consider a bookmark, I guess? I don't think I actually bookmark things other than to get them in my bookmarks bar for easy access. I do, however, use Apple's "reading list" feature a ton because I stumble across papers and blogs that I do want to read but I just don't have the time right now to read it. It's less a curated set of bookmarks and just a bin of things to read on the train.