Think about some of the hot topics or genres of yesterday-- vampires, witches and wizards and boy wonders, orphan children going from one unfortunate adventure to another-- and then tell me what they have to do with today.
Nothing! Don't write about yesterday's hot topics just because they were hot. If you must use them, do it because you have a passion for the story and can write about it well. For no other reason. Certainly not because they were hot once. The market is flooded with vampire stories, so if you're going to write another one, better give it a new twist.
"Never give up. And most importantly, be true to yourself. Write from your heart, in your own voice, and about what you believe in." ~ Louise Brown
"Write something to suit yourself and many people will like it; write something to suit everybody and scarcely anyone will care for it." ~Jesse Stuart
"A writer's job is to take one thing and make it stand for twenty." ~ Virginia Woolf