Blizzard cycles in and cycles out cards for Hearthstone regularly. New cards and characters can drastically alter the way the game plays, and they actually attempt to work hard to keep the game as balanced as possible, hence why they're retiring certain cards.
According to Kotaku, it's been confirmed by Blizzard that neutral class cards including Azure Drake, Sylvanas Windrunner, Ragnaros the Firelord, the Blackrock Mountain, Grand Tournament and League of Explorers expansion sets will all be removed from ranked play and retired to the wild set. According to the article, players will still be able to compete using either the standard set or the wild set, but only the standard set in Hearthstone will apply to ranked play. So any competitive players will have to get in their time now with the sets that are being retired if they want to continue to stay competitive.
Blizzard has plans on retiring the aforementioned sets this upcoming spring. You can still dive back into the sets in standard play where wild sets can be traded into your deck, but Hearthstone's ranked play will get a complete overhaul, and by complete overhaul, I'm talking three sets of card decks containing 130 cards each.
According to the post over on Battle.net, Blizzard explains that the three sets of card decks will roll out over the course of all of 2017 as opposed to releasing story-oriented expansions like they did in 2016. The first 130 card set will be available this spring, the second set will be available in the latter part of the second quarter of 2017, and the last card set will be available at the tail end of 2017. All three decks will contain 130 cards.
To compensate players -- especially competitive players who want to get up to scratch and into the ranked ladders as quickly as possible -- Blizzard will be handing out free dust to Hearthstone players for every card in their deck that will be retired to the wild set. So even if you have the rare Golden Ragnaros card, you will still be rewarded with 3200 dust. If you have multiple rare or legendary cards in your set that will be retired, you will receive dust for the equivalency of those cards' worth. The best part about it? You won't lose your cards. You'll be able to keep your cards... except you just won't be able to use them any longer in ranked matches.
While some competitive players might be fuming at this news because they built up the perfect deck collection, this is Blizzard's way to keep the competitive eSports scene both fair and exciting in Hearthstone. That's not to mention that this also opens up great opportunities for newcomers and eSports freshmen.
A lot of times some games have skill levels in the competitive scene elevated so high due to all the adjustments, readjustments and incessant studying by the top level players that they know the game inside and out and it makes it hard for a lot of new people to get in and get good enough to be a viable threat. Blizzard's tactic of purging lots of cards from the decks and setting them to the wild while being in large swathes of new cards means all Hearthstone players will have to make adjustments equally, and do so at three points throughout 2017, giving a lot of players equal footing to get good and climb the pool ladders to the top.
And don't worry, Blizzard will be fostering smaller tournament organizers using the wild card sets to keep the older, retired sets in play for those who still have fond memories of their old Hearthstone decks.