It looks like The Elder Scrolls: Legends is on its way to shutting down. The game's community manager announced in a recent Reddit post that the studio has "decided to put any new content development or releases on hold for the foreseeable future". In the short term that means the cancellation of an expansion that was planned to arrive in winter 2019, in the long term it means the game is probably heading toward a quiet end.
The Elder Scrolls: Legends could always return to a schedule of regular content updates, but such revivals are sadly uncommon for most online games. Legends will remain online and playable for both new and existing accounts, and it will also continue to have in-game events and monthly reward cards for players - "new expansions and other future content, however, are no longer under active development. We will continue to provide ongoing maintenance support."
The Elder Scrolls Legends first launched into beta on PC back in 2016 and has since come to consoles as well as Android and iOS [Correction: Console versions for the game were announced, but they still haven't come out, and probably will not at this point]. A range of expansions linked Legends back to Elder Scrolls lore established in games like Skyrim while also expanding it. The game's current developer, Sparkypants Studios (that is its real name) took over from former steward Dire Wolf Digital in May 2018. Both worked on the digital card game under license from Elder Scrolls parent company Bethesda.
So far, Sparkypants hasn't announced any changes to how Legends will handle microtransactions in response to active development winding down. Hopefully that means the game has a good amount of time left before the servers shut down and it's made unplayable, at least.
If you're looking for an alternative online card game to jump into that isn't Warcraft shaped, check out our guide to games like Hearthstone.