Don't dismiss .NET itself so easily. As you can see from this incident, there are elements even within Microsoft that don't inherently value the open source nature of the .NET team! .NET Core/.NET 5+ are already open source and highly philanthropic in nature. That doesn't change just because a completely different team--the Visual Studio team--is profit-oriented.
I learned to program with C# back in 2007. I have been following .NET and C# for more than a decade now, I look back fondly at my time with the language and people there. However, if the team is having this much internal struggle why would I ever come back? Why would I stake my business on another Oracle when there are much better alternatives?
Can you point any useful, non-esoteric language with a thriving ecosystem where the internal team doesn't have problems? I don't think so. For real drama, check the history of some well-known compilers/suites (such as the whole gcc vs egcs debacle), you'd be amazed.
All languages have had problems, some are resolved, some are not.
Ruby I think has managed to avoid very material conflicts.
Python hasn't, it's a comparative shit-show.
Java had -huge- problems in the past but was able to move past them and is stronger for it.
C# is in wait and see territory for me. I -really- love the language and tools but if I had to start a new company today I would probably go with JVM stack until this sort of stuff is sorted out. A few years from now I hope I will be saying the same about it as Java.
Maybe it sounds egotistical but for me it is a perfect fit. I know they will support running .NET on Linux because of Azure. I know they will support cross platform development with MAUI because they want developers and market share. It's not like they force me to target Windows Server with only SQL Server available as a data store. I don't plan to give up Visual Studio. So I don't have any reason to abandon .NET and C#.
Also, C#/.NET is kind of jack of all trades, you can do anything but a small subset of development where having a garbage collector stays in your way.
As for alternatives, I dislike Java, Python is less performant and not usable for large projects, Rust, Nim, Haskell, Elixir are not as usable and well polished. Kotlin is nice but it does not have any benefit over C#.
I would love for Rust, Nim, Haskell, Elixir to pick up some steam, become more usable, have larger communities, much more libraries. But until then, C#/.NET is the sweeetspot for me. I still dabble in C/C++ from time to time and that makes me grateful C# exists. I am even inclined to double down on my .NET bet by starting using F# along with C# because it feels like a very nice language. It seems to enable even faster development while being more concise and needing less tests written.
