Time and again I keep being impressed with your selfless commitment to building and sharing things in the most humane and long-term way. A beautiful example to set, thanks.
And yet they haven't open sourced the app. That would be truly humane and long-term. As it is, it's just another proprietary app that, if it dies, can't be continued by the community.
I don't think monetary issues should be a concern with open sourcing the app - companies like Bitwarden, Gitlab, and New Vector (the company behind Matrix) are doing just fine with their open source products.
Your data isn't locked up in a format. Just use logseq or something if obsidian disappears.
Those who write the code have the right to control its source code. They aren't "inhumane" or thinking "short-term" just because its not open source.
The jury is still out on "companies like Bitwarden, Gitlab, and New Vector". Kudos to them for pioneering novel business models.