It'll be Java on the server to replace the PHP on the server. Nobody writes Java applets any more. If they do it will be the end - do Java applets even run on phones? I've not seen one (by which I mean a "You need a Java Applet Plugin" placeholder) for years.
I just take issue at the "Most Importantly". How is that most important? Because the end-user shouldn't care. The only people to whom its most important are the Java devs getting the gig. I suspect the PHP devs getting their final wages might be a bit upset. But then again, maybe Y! don't bother maintaining the code and retaining any PHP expertise.