If it ever comes to needing an Obsidian replacement I'd hope it can aim for compatibility with the plug-in ecosystem, at least initially. No idea how difficult a target that would be. Either way, I certainly worry about my data in Obsidian less than I worry about Evernote, OneNote, or Apple Notes, even with a couple of non-standard markdown additions.
Since it's not VC backed I'm hopeful about Obsidian building a long-term sustainable business without having to turn shitty, but who knows. I should sign up for Sync and give them some money.