Bethesda released The Elder Scrolls: Legends years ago, as an obvious response to the success of HearthStone: Heroes of Warcraft. The success of Blizzard's card game made every company want to gain a foothold in the card game market.
Many of these clones mimic the turn-based mana system, which although based on Magic: The Gathering, It was Hearthstone who popularized it in video games. It also uses being in a video game to have more complex effects than a physical card game would have. But in this market there is little room for competition.
It's not canceled, but there's nothing for now
Bethesda has announced on The Elder Scrolls: Legends official reddit that development of all content and major updates has been frozen. It does not mean that they are going to shut down the servers in a year or two, but that we do not expect content that is not minimal support and critical bug fixes.
Players will be able to continue playing The Elder Scrolls: Legends and participate in monthly challenges. But the game won't move forward because there are no plans for expansions or meaningful content for the card game until Bethesda changes its mind. The console ports that said they would arrive at the end of 2018 will very surely not happen.
The last update was widely criticized because it gave players a great advantage using the new mechanics they introduced, something that makes the community feel left behind in a card game as there are no strategies to counter it. There are currently no plans to retake content for the game. And seen how busy Bethesda is with games like Fallout 76, Starfield, and the next The Elder Scrolls, it doesn't look like Legends is going to resurface for a long time.
Source: Kotaku