Then again, any language should meets your criteria. You don't have to use the new features.
Unfortunately, this leads me to conclude that almost nothing is safe for the long term.
Older Elixir would 100% backwards compatible and any type system (if there is one,) would be gradual.
https://elixir-lang.org/blog/2022/10/05/my-future-with-elixi...
It's an optional feature.
https://devblogs.microsoft.com/vbteam/visual-basic-support-p...
Visual Basic 6 applications are supported up to Windows 11 but the IDE is not:
https://learn.microsoft.com/en-us/previous-versions/visualst...
What do US nukes use? Anyone?
This barely sees updates except minor things and security patches, works great.
But yeah HTML by itself is pretty fixed now and new stuff happens in CSS and JS.
HTML and its purpose is dying.