There's 2 events one on Friday and the other Saturday (atleast in my timezone) the first is the announcement showcase which is going to be roughly an hour long and cover about JP and NA fanfests if I have my info right and the one on Saturday is the part 1 of the 5.5 live letter. So I would assume that we'll see quite a bit depending on how much time the usual info dump will take and every expac has a new feature touted with it that they will inevitably announce on the 5th but that's my most realistic take in this.