From the title of the article it's pretty clear what's going to happen: Hearthstone Beta accounts are going to be wiped, but wait there is more...
An official announcement was published a while ago about this. Seems like a big Beta Update comes for Hearthstone and it will require an account wipe. Basically all your progress will be reseted. I mean everything: your rating, cards and levels of your heroes. This reset will take place only for EU and US servers.
Those of you who spent real money to buy card packs are going to be reimbursed with gold after the reset. This way you'll be able to rebuy all those packs right after the reset.
The legendary Golden Gelbin Mekkatorque card, if you have it, will remain and it will wait for you after you finish the introductory battles.
For the moment there are no details about the future update, but since they are doing a wipe we can expect something big.