That Harry Potter kid sure can sell books! To a significant extent, this is good for writers; however, the "blockbuster effect" is also bad for writers. Too many marketing dorks will try to clone Harry (something that the Ministry of Magic would frown upon) instead of allow writers their own voices. As a specific example of problems with this, consider what has happened to Tolkeinesque fantasy over the last quarter century. When Terry Brooks came out with the awful Sword of Sha-na-na series in the mid-70s, proving that a clone could be done and could make (and continue to make) money, that was not so bad itself. At least it made commercial publishers realize that wizards and elves weren't just for Disney. However, the next set of clones showed all of the problems one expects from inbreeding (e.g., Dennis McKiernan). This isn't just limited to speculative fiction, either; there is a clear chain from Turow onward in the post-Perry Mason legal thriller, and the less said about the so-called "mainstream"'s problems the better.