I doubt it, because halo is to violent of a game for Lego to come out with. But I've seen a few on eBay, which are fan made. But no, it will be unlikely for Lego to push forward a Lego Halo.
I read that there will be 2 new themes called ninjano and pirates of the carrabian.
So far the only Harry Potter set is 10217 Diagon Alley, but there should defiantly be more coming soon!
It was one of these they both came out in 1965