I only have two:
1. SoU will be very impactfull like Kobolds or Naxxramas.
2. Zephrys is gonna get nerfed.
As a veteran player (playing since beta, got legend) I dont like arena because I love to build fun decks and try new things. If you are not into grind constructed is the real fun. I finished last season at rank 4 with a homebrew wild espionage rogue deck and had really good time. I know seeing same decks over and over is nerving, I hate netdecking with all my heart but this is inevitable. People want to win, I want to have fun and some people just have fun from winning. For me meta is fine, there is diversity but stale. When Rastakhan drop this will change. People are very negative and dissapointed because of the game has so much potential, should be way better (I agree with that). I think hs, especially constructed is good but the grind is killing fun.
Put a random The Lich King in there because why not?