Am I wrong or is OP describing most of what swift currently offers. Optionals, extension where syntax, Result<> monads, exceptions collapsed to a single line with try? syntax, safe casting with as?, etc...
Having higher kinded types and type classes like Haskell would be nice though. I think there are definitely things in the article which could be even better, but we've definitely moved that way, and the next generation of language designers will probably have even more insight into how to elegantly combine those features as well.
Don't have to leave the JVM, already there in Scala. And Kotlin Arrow may get merged into the compiler, so Kotlin may have first class support for these language features one day...
At some point, I realized Java code tends to have many more runtime type errors (in particular, NullPointerExceptions and ClassCastExceptions) than similar C++ code (segfaults). Things like rust should be even better than C++, but that’s practical largely thanks to performance optimizations from llvm. Other than Java compatibility, I don’t see any advantage to the JVM at this point.