It's not clear that bytecode changes are needed for efficient pattern matching support. Java is getting pattern matching support. The related JEPs mention that:

It's not clear that bytecode changes are needed for efficient pattern matching support. Java is getting pattern matching support. The related JEPs mention that: The implementation will likely make use of dynamic constants https://openjdk.java.net/jeps/309 https://openjdk.java.net/jeps/309 I strongly suspect that Scala could be more efficient if it used it too. However I have no idea if this could improve compile time. (kotlin has until now procrastinated implementing pattern matching support because they say it increase compile time, but maybe that doesn't hold with constant dynamics)