During the recent announcement for the Journey to Un'Goro expansion Blizzard stated that they will soon start ramping up the amount of cards entering Hearhstone, essentially going from two to three large expansions each year. If you were worried this whole process would make Hearthstone far too expensive for you, I'm afraid I bring some bad news.
According to an official post on the European Hearthstone forums the prices for card packs, adventures, and arena entries will be going up on March 22nd. The current price for 2 card packs is €2,70 for the general EU audience, while under the new system it will be €3. Consequently, 60 packs will set you back €70 instead of €63. Things are a bit less pleasant for those of you that hail from the UK, however, because the price of 2 packs is going to increase by an entire pound, going from £2 to £3!
If you're interested in how this will affect you there's a brief overview of the price changes for each country and currency over at the Blizzard website. On the positive side, the price of the Un'Goro prelaunch bundle will not be affected by this change and will cost exactly the same until release.
As for the reason behind all of these price changes, here's the official statement from Blizzard themselves:
"We’d like to let everyone know that we’ll soon be adjusting the pricing of Hearthstone purchases made through the PC, Mac and Android clients, and through the Battle.net Shop. We regularly look at our pricing around the world, and from time to time we make changes such as these to align with local and regional market conditions."