Not with their core languages. For example, Windows still comes bundled with the old VB6 runtimes and Microsoft still supports the language even if they no longer add features to it. I'm not really sure of any major Microsoft languages that Microsoft has just dumped, unless you count their smaller more esoteric ones.
Also keep in mind that .NET Core is not only open source, but comes with complete protection from any patents Microsoft might have. The only thing Microsoft can sue people over is the .NET Core trademark itself.
> still supports the language even if they no longer add features to it
This is what I assumed the parent post was referring to. Mostly because it mirrors complaints I've heard (and maybe had) about the .net gui story. WinForms -> WPF -> whatever the windows store app framework was called -> I think MAUI now?
That's hardly a fault with Microsoft though. WinForms is fundamentally flawed and far better alternatives now exist, it'd be foolish to continue investing in WinForms. You can still use WinForms and .NET Framework on Windows 11, just don't expect new features, which is okay.
Wasn't J# designed to be a transitional language for Java devs migrating to .NET/C#? (Wikipedia calls it a transitional language, too) Sure it wouldn't last long.
Also keep in mind that .NET Core is not only open source, but comes with complete protection from any patents Microsoft might have. The only thing Microsoft can sue people over is the .NET Core trademark itself.