It occurs to me that the DA might be a kind of precursor to Harry officially teaching remedial DADA next year. Because he's proved himself as a teacher now (just look at the results he got from Neville!) and they won't have to keep it secret any more, with Umbridge gone and the Ministry having accepted that Voldemort's back...
So maybe that's when we'll see some decent Slytherins and real house unity. Maybe they'll come to him, since Hermione obviously wasn't willing to recruit them.
