Makes more sense for Universal to be quiet right now. Disney has fired their shots (my opinion too early) and now will have to keep the momentum up for all that time while keeping guests that have to deal with the construction happy. Avatar was a huge deal back when it was announced and never got back up to the amount of hype it had. Universal is good at playing their hands close and it has paid off for them multiple times.
My thoughts on HP vs Star Wars. Harry Potter is the more successful franchise from here forward. It has more successful movies, younger actors/actresses enabling additional movies, and nothing but love from the fan base. Star Wars had 3 good movies, and a ton of controversy behind it. Maybe these next movies will be good, hopefully they will. From a marketing point at this current moment though, there could be nothing that could beat Star Wars and take that amount of hype away.