Java is the default language in the best selling phone platform, Android. For that reason alone it will remain relevant for a long time. I know Android can run other JVM languages, but until the platform becomes stabilized (meaning most big security holes are filled, new non-trivial features are rare) there won't be a push to make non-Java languages a first class citizen.
You are eliding the difference between selling a lot of devices and selling a lot of apps. I notice this ecosystem over here that's running on Objective-C that's doing a very good job of selling apps and directing money towards developers.
Android is certainly going to help Java remain relevant, but this is another example of how it isn't highly compatible with the entrepreneurial mindset. The Android app ecosystem isn't as good at rewarding independent app developers as the iOS app ecosystem is. So people who, in entrepreneurial fashion, want to be judged by the market, will probably make iOS apps because that's where the money is. I argue that that'll produce a 'brain drain' away from Java - Java will be the language a day job makes you use, and something else will be the language you use for projects that you care about.
The projects that people care about, in the long run, are far higher-quality code than the projects that they only do for a paycheck.
I think you've been asleep for the last year or so. This is not even about Android vs iOS, I don't care about that stuff. There, clearly, is a large interest in developing for Android (again, whether it is on the same level of another platform is irrelevant to Java's future viability). Real, good developers are taking it seriously, and profiting.
Actually, Go would be great for GUI programming, precisely because it has a concurrency model that doesn't suck, and GUIs are almost always concurrent. Remember that Go's concurrency model is a descendant of CSP which Rob Pike first used in Squeak, a language designed exclusively for building GUIs: http://doc.cat-v.org/bell_labs/squeak/
> Java is the default language in the best selling phone platform, Android.
When iPods and iPads are included, iOS greatly surpasses the Android install base. These aren't just phone operating systems; they're mobile device operating systems.
