At least Lynch has finished the 1st draft for book 4 ; it has been almost 10 years since Rothfuss' last book. Basically his head isn't in it anymore, and I don't think the third ( and supposedly final ) book will ever appear. As for GRRM, mentioned earlier, I don't think he'll finish ASOIAF either. Like Rothfuss he's lost his mojo and given his age, and writing speed, will likely die before he can finish book 7. I do think we'll get Winds of Winter, though.