[username91]

I'm not aware of HN doing any predicting at large. If you mean 'will the average person later act like a given segment of HN people do now?' - then it depends on how good you are at selecting your segment, which makes it no better or worse than using any other sample of people for prediction.

Less abstractly, productisation is what takes things from obscurity (e.g. HN) to mainstream audiences, so future trends might grow out of stuff that you see here, but the people who can figure out whether certain tech can become a product (would-be predictors) -hopefully- also have the means to turn it into a product themselves.