Java running in the browser is unlikely as typescript has largely tamed the mess of Javascript. Java requires a JVM and shipping an entire JVM so its runs atop another VM is kinda redundant. Except if JVM itself gets compiled and cached as a WASM bundle and Java compilers start accept WASM-JVM as a target. That will just be distraction tbh, Java has its strength in large scale systems and it should just focus on those rather than get caught up in Frontend's messy world.