Hearthstone just announced a couple of new huge updates to the game.
First, starting with the next new expansion everytime a player opens up a pack with a new legendary card it'll be one the player doesn't already have, this also includes impunity when crafting a card! This will make the pack opening process even more exciting especially when it comes to seeing a card with a golden border.
Second, starting with next expansion everyone will be guaranteed to open a legendary card within their first 10 packs of the new set.
I think these are smart moves for Blizzard, with the first update there's more incentive for players to purchase packs since you cannot get repeats. With the second update players who cannot afford to purchase 60 packs as soon as a new expansion comes out will not be left frusterated since there will be a guarantee of recieving a legendary within their first 10 packs of the new expansions!
Additonally, starting within the next few days players can login to Hearthstone for a limited time promotion where the price of packs stay the same but the amount increases!