Obsidian and plugins do not really lock in anything - that’s the beauty of Obsidian and one of the biggest selling points for me. Let me break down the way I choose tools.
TLDR: Obsidians way of handling your content is the best possible way for future-proof data retention - all other options are worse.
Do the developers have an income stream to support development long-time?
Open-Source is great, but life’s strange. Everyone has a breaking point in life when continuing to work on open-source for free is not sustainable anymore. Companies may fail as well or be bought, but the risk of not being able to work on a project anymore is much more common without a revenue stream.
Obsidian is developed by Dynalist Inc, has several streams of income
What happens if development is stopped?
Obsidian is not a service that can be deactivated or deprecated - it and its plugins run locally, so even if something happens, it just keeps running. In stark contrast to online services.
Nothing would happen, so great
What happens if Dynalist starts to charge or change the license or do ?
Same as before, just continue using your local copy.
What if I really cannot use Obsidian anymore (kill-switch, security issues, ?
Markdown as the Domain-Specific Language (DSL) Obsidian and the plugins use and extend is standardized and easy to grasp. Since its just text-files, it’s easy to move files into any new order you like and use search-and-replace or Regular Expressions to rewrite your content to a new format of any tool that you might want to use to replace Obsidian. This is in stark contrast to pretty much any other persistence method (online, databases, etc.). Just ask NASA - they had refound some old data tapes from the beginning of the space race in a cellar, but were unable to read them anymore and had to spend hundreds of thousands of man-hours to reverse engineer the format again.
And while it surely would be cumersome and breaking your workflow for some time, the worst case scenario is having to spend more time to do everything manually. With most other tools, the worst case scenario is loosing everything.