I can understand conservative choices when it comes to picking a language but what you describe is a potential risk for plenty other existing languages as well as any new language too. Rust wouldn't be where it is today if it wasn't sponsored by Mozilla. Java was Sun Microsystems baby and I remember all the concerns at the time with the Sun vs Microsoft fighting over control of the ecosystem. Plus even many of the non-corporate languages are still heavily dependant on a small subset of maintainers.

At the end of the day if a language proves popular enough in other domains outside of the area which is directly controlled by the language maintainers, then the community will usually find a way of taking over maintenance of it.

We've seen this with Pascal, various BASIC dialects (including Visual Basic), and to an extent Java too. The problem with Objective-C was that - as far as I'm aware at least - it wasn't widely used outside of Apple / NeXT's ecosystem so if Apple deprecate support for Objective-C on their own platforms then there's little incentive for the community to keep using language (much like the problems with Visual Basic - which is why few know about it's open source forks). But languages like C# and Go are used massively across a multitude of domains so even if MS/Google were to kill them tomorrow, the community would almost certainly find a way to keep language alive. Heck, Go might even become more popular if that happened since many of the complaints against it are down to the highly opinionated approach of the current leadership.

Let's also not forget that Go and C# tooling are open source so the community wouldn't have to reinvent the wheel like they did with Delphi / Object Pascal and Visual Basic.