I think that what is going to hurt Triple Triad the most in the future is its lack of scalability. PvE content can always be made more difficult by increasing the numbers; bosses hit harder, mechanics do more damage. It has room to grow and expand. But TT cannot scale further than it already has without breaking the fundamentals of the game and allowing for number values higher than 9. This is why HW saw so many "unrewarding" NPCs in 3.0: the only way for the devs to inject challenge into the content was to remove a great deal of guaranteed strategy and forcing players to rely mostly on luck. They relented on the random rule in 3.1, and instead nerfed drop rates hard to keep the timesink.

As a result, for as long as the devs continue to support TT, every patch will see a slew of "new" cards that are objectively useless. Combine this with a lackluster implementation of Tournaments, I've pretty much written off TT unless it gets an overhaul in a future patch.