On Valentine's Day, ESL TV streamed Day 2 of IEM Cologne. During the tournament, there was an interview that took place with Kim Phan who is Blizzard's eSports Senior Manager.\
At the 9:20 mark of the interview, the interviewer asks any features that will be added to Hearthstone. Kim says when the game is officially launched shortly out of beta, spectator mode will be available due to popular demand. She also mentions there are additional features to come.
Hit the link to see the interview in full about Hearthstone and Blizzard's view on eSports future.