It may still be a little early to say for sure on it, however I have played a good number of free to play games and the like.
On one hand, I LOVE the fact that the rewards actually feel meaningful and are actually noteworthy. On the other, I feel that this may lead to a stagnation of players who will simply log in, log off for the rewards, and not much else, feeling that they do not need to play any matches to reek the benefits (Excluding IP boost).
In my opinion, as far as the kinds of rewards you receive, you guys are definitely on the right track, however the incentive should carry over into actually playing the games instead of feeling like a login bot for a multitude of games (Was feeling like that for awhile when I began to burn out playing Neverwinter and Firefall).
What would I do? I feel that that as far as logging in, you've definitely upped reason to do so. To continually play? I feel that there should be alot of extra 'quests' to do to gain cards other than the academy and campaign. Things that would correspond to the different factions such as "Discard 50 cards" Get cresill, the mad, discard 150 cards, get a copy of hungry abomination. discard 500 cards, get a copy of yagron.
Another example would be awarding the cards to overseers for removing X characters from game, or cards to sleepers for bringing back X number of cards from the graveyard into play, or flame dawn for hitting the players fortress with characters played that turn X number of times, ect.
It would help flesh out harder to get cards for newcomers as a guaranteed means other than trade, and give them a goal to continue attempting to get, while also letting them explore the different play styles of each faction.