Why do you think that the Young Adult genre is so popular with even the adult readers? Do you read YA books, yourself?
I love YA books and making even a small transition to adult literature has been quite 'unsuccessful' for me. I found myself returning and hungry for more. I think the reason why YA genre is so popular is because of the many fascinating stories the genre has. Somehow, YA books reaches to everyone more broadly than that of adult literature and each story offers new surprise, excitement and adventure of its own. Adult literature tend to deal with heavier subjects which adults themselves don't even seem to understand (so how can it reaches to everyone?), unlike YA books that mostly revolve around romance and interesting characters everyone can easily fall in love with. I believe YA literature will always be every reader's top choice of genre to enjoy and with many new emerging YA authors these days (of course with new ideas and stories to tell), I can't see why YA books aren't able to conquer our modern day literary world.