After some thought (and the license update on their end), I think that Standard Notes meets all of our criteria and shouldn’t be removed.
For plain-text and Markdown functionality with the Plain Text, Super, and Markdown editors, the per-file export works exactly as expected, and the bulk export/backup option is fully functional (albeit slightly janky). This is on par with our other recommendations, and other filesystem-based note-taking tools we are considering like Obsidian.
Editors which are unrelated to note taking, like Spreadsheet and Authenticator aren’t quite as nice, but for the purposes of our criteria in the Notebooks section we’re not going to consider them as a reason to remove SN. Think of them as a bonus for paid users maybe, but there’s a reason Standard Notes Spreadsheets isn’t included in the Productivity Tools page.
I’m marking this suggestion as rejected, but—as always—this thread will remain open if anyone has further thoughts. And I’ll post an update when I figure out the answer to my self-hosting-related questions, but those questions weren’t going to be a deciding factor on whether SN gets removed or not.