You really think there's even a chance that java will be 'largely irrelevant' in 1 year? Maybe you should try assessing your prognostication skills by writing down your predictions for 1, 5, 10 years out and see how close you were. I have a feeling you're just as liable to make mistakes trying to guess what will happen in 3-7 years as you are using the best tools at hand today. Whatever you think of java, for example, google 'java is dead' and see how well people have predicted the future. It's still going strong in the enterprise, and even a lot of startups probably do some java in the form of Android apps. Flex has some great things going for it. It's only easy now in hindsight to say that four years ago you took the wrong path.