its my guess that all of the decks released in the past 2-3 months were designed/produced from 6-12 months ago when we didn't see releases every week. whether by chance or design they all "made it to market" within a very short time frame. Once the larger card producers see a lag in sales (could be now or in the future...who knows?) and the market for playing cards levels out, I think you may see the reverse happen. I believe we may go back to at least 3-4 months between major releases. Unless I'm mistaken...and I could be...I don't see how we can continue to see large releases anywhere close to the time frame we see now. The game changer in all of this is the kickstarter method IMO. If people like the deck its sells and gets produced...if not...no cards. You don't have to worry about spending a boat load of money on cards for them to sit in your warehouse.
The deck releases were indeed timed - all near the end of the year, coinciding with the biggest shopping orgy on the calendar, the Christmas holiday season! And of course they were in the works months ago - decks don't go to market overnight.
Kickstarter is still a small though growing factor in the cards market. Last year they had exactly one deck hit the market, and they've had a roughly equal record of success and failure regarding play card projects. Granted, the ones the failed for the most part deserved it, but still. As time goes on and more Kickstarter decks are actually in the market, then we'll see what effect it will have - bear in mind that one deck, Brimstone, has actually made it to market from KS all of last year. Wait, make that two, but the other is a deck of burlesque striptease artists called "Play Me Burlesque", so it's hard to count that one...