I doubt that, devs can switch Code, Shure some game devs need to remake already written code but i think there will be someone making a code translator right now.
Even if you could just "translate" code from one language to another, that ignores asset pipelines, asset store libraries, and all the build pipelines that allow you to ship cross-platform.
You also need to now train your entire dev team on a new tech stack.
If you can do it with databases you can do it with most other code. Shure it won't be problem free but way better than bankruptcy. And users will understand that it might be buggy for some time if you explain it to them.
And yes you have to retrain your staff but its their job.
And of course there will be library issues but there will be someone making new libraries.
Im not exactly that sorry for most tbh, there have been many other languages and engines that aren't unity, they have been doing shit for years now, people could have switched already. This now is just tip of the iceberg basically.
Im only sorry about small studios and indie devs that worked on something for years and now that.
I'm using Godot 3 for my current project because even the relatively minor changes I'd have to make to port it to Godot 4 would be unfeasible. If I had to change engines entirely I'd have to just abandon the project.
One of the biggest appeals of modern gane engines is that you barely need any code but that also means everything is centered entirely around the game engine, I doubt there is any way to transition that, it probaly means devs have to start from scratch and reimplement the mechanics.