> By the time Java 8 rolled around they definitely were "traditional".
Based on my experience only once CompletableFuture was added to Java did the Future interface really start getting used in mass. Before that, there were other libs that implemented Future like things (Rx, Guava, Netty, etc) but they were not adopted across the board.
The transition to Java 8 was night and day! Roughly on par with the React Hooks transition.
But lambdas and everything coming in project amber, yeah, there will increasingly be many styles of Java out there.