I can tell you if Godot abandoned GDScript and went all in on C# then I would stop using Godot. I do not think C# is even remotely enjoyable as a language and GDScript works really well.
Personally I find C# to be a fantastic language with both high (eg. pattern matching, dynamic) and low level (eg. value types, Span<T>) features as well as amazing tooling (eg. Rosylyn Analyzers) that come in very handy.
If performance is an issue, or I want to do something that GDScript doesn’t lend well too, I’d probably just jump to C++.