Hearthstone's forthcoming expansion will introduce over 100 new cards to the game, according to production director Jason Chayes in a Polygon interview.
The single-player-focused Curse of Naxxramas was well received but Blizzard is aware that card games come into their own when played with others and Chayes says:
"I think we're going to mix it up a little bit with this next release, which will be our first expansion. It will have a lot more cards. We're talking about more than 100. We are going to have a central theme for how that will all fit together. That'll be the next thing coming up."
He adds that more content is planned in future but you shouldn't expect too much too soon. "We really want to make sure the pacing is great not just for seasoned Hearthstone players but for new players coming into the game too," Chayes comments.
Another concern is how many cards they can add before they've introduced too many and are forced to bring in restrictions on what can be used and when.
The developer notes that "If we do reach that point because there are just that many cards in the available set, one of the things we definitely want to make sure of is that there are ways to continue playing with all of your cards, and that it feels really good to be participating in these various modes."
Chayes says we can expect more news "very soon" and with BlizzCon set to kick off on November 7th we may have some information on what to expect in just over a month.