Flat design, bacon cupcakes, dubstep, hand held cinematography and more - they will all die. The best trends will evolve into something new but most of them are going to fade away. Don’t worry, ideas are cyclical and if there’s value to the trend it will be reincarnated some years down the road. In fact, your current favorite trends are probably ripples of an idea from a previous decade.
Predicting the directions of trends is like a Choose Your Own Adventure book. Let’s use Flat Design as an example: There’s already buzz that it’s time to move on and tentative arguments for skeuomorphism are resurfacing. So, either Flat Design will evolve or there will be a strong reaction against it and something like David Carson’s design will emerge as the next trend. Evolution or opposite reaction. Take your pick.
Now for the hard part. Taking action on your prediction in a way that resonates with an audience.