I LOVED Triple Triad in FF VIII. However for an MMO the card game needs to be a lot deeper. As for the concept of having our own trading card game in game to play vs npc's and players, complete with trading/selling and even competing in ranking leader boards and tournaments, how could I not love the idea. I can imagine a play in XIV's Golden Saucer dedicated just to let players spend hours away challenging each other.

I would love for them to make their own original game with an emphasis on card variety to really make each players deck shine powerfully yet be unique, like Magic/Yu-gi-oh/pokemon ect. no cookie cutter builds. Triple Triad suffered from a bad case of "Must use" cards and "Sure win" deck strategies.