It's very exciting when zanz announces new cards and you get to try them out in the trainer, and then there is a 15 page discussion in the In Development section building anticipation until... the card is released and you buy it in the bazaar. Meh.
My suggestion is that new cards should be released into the game through the spins from the AI. I don't mean to add every new card to every deck like in the Trainer, I mean tweaking the spins so that every once in a while you win a new card. It would work like a wild card, you don't need to match all three but if the new card comes up once - you win one for your collection. This would happen every 20 or so wins, and once you had the card it would be like normal so they could then be spread via the current T50 and PvP1/2.
Also, different cards would be released on different levels. To parallel current events, in patch 1.27 Ghost of the Past would be in AI3 spins, Acceleration would be in Half Bloods spins and Mitosis would only be in FG spins. And then finally when patch 1.28 comes out, Ghost, Accel and Mitosis would be added to the bazaar and the next batch of cards would be pre-released on the AI.