I think that kind of writing (if not done by JK) should stay within the realms of FanFiciton. I think Jo is right in her decision not to write nemore Harry Potters than the 7...u have to know when to let a series die out (not that i think the potter series will ever leave us...look at how popular star wars is...and tats not including the EU writings) JK always intended for there to be 7 books, and when you start stretching it out, usually the series takes a turn for the worse.