the problem with what you and minsc are suggesting is that, what happens when IAP sales fall off a cliff, like they do for every collectible game? your expected frequency of expansions would basically mean they have to go (numbers from my ass) like 6-9 months without any major revenue once those sales fall off. Hence why CCGs see fast updates.
The other thing I don't understand from you guys is that the reason PC/console games SEE new content at a snail's pace, is because there is usually considerable programming and design aspects that have to happen not to mention a ton of technical QA.. much of which is largely absent from updates to a game like this. You have art (which I am sure there's a TON of existing 2D art at blizzard), maybe a new mechanic or two, and then a ton of cards all working within the existing mechanics (plus the new ones). Nowhere near the hurdles your typical DLC has to clear before seeing release.
I'm not saying you guys are wrong. On the contrary, if you are right I'm simply saying I don't see how blizz will be able to keep this service profitable. they need money coming in, and frankly it comes from guys like me. Well, after $500 so far, I'm done, and that's an outrageous amount I know. Which means people paying less are more likely to be done paying even quicker. Not sure how yuo guys see money continuing to come in at a rate to keep the game/service afloat based on how often you expect new paid content to be released.