In my opinion a solution for the game's staleness could be letting players play more cards. This result can be achieved in a bunch of different ways
1) As you said, mini-releases, like the one Blizzard did in the past with Marin the Fox, but much more consistent and frequent
2) As some people suggested, more expansions: 4 each year means a different meta every 3 months, which could be good
3) Change the rotation system: if we rotate one expansion at time, more weak cards could see play, giving a feeling of freshness
4) Reduce packs' cost: in this way, people that don't invest tons on money into the game will be able to get more cards and actually experiment new combinations. Being F2P or nearly should leave you the chance to play competitively without being insanely greedy. Moreover, if more people are able to test new decks, more archetypes are likely to show up.
As long as Blizzard decides to do something for the sake of the game I'm ok with that, but they should shake the things up a bit since not only Standard's meta, but even the whole game is beginning to feel very stale
Yes to all of these!
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Just made a control shaman deck that included 2x echo murloc 2x Mr. infinity murloc and 2x slurp. Great for early game control and mid game WTF moments, many of the games are straight up no contest... especially when they realize it's not a murloc deck.
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The inner geek in me will always love Hearthstone. Three times a year I get a lil' mini rush of nerd hormones pumpin through my system, the thrill of imagining how various aspects of my collection will be augmented or made borderline useless by the changes to Standard (sadly I've more or less abandoned wild despite playing since launch and having a decent number of cards in that format).... but gosh darn it I need more. I feel like mini releases of single cards would be a sweet way to go, just to keep interest piqued. Or perhaps rolling out expansions over like a month or so like the old adventures used to do so that things aren't quite as staggered. I love the game and wil probably play it for years to come - I guess all I'm sayin is I want to be more addicted to it ;)