Everything Delta is doing with regards to first class cabin size and pay-for-use Medallion requirements is all in lock step. Don't think there isn't close collaboration on items like this. One key to all this is what I call misleading marketing and communication - one of the single biggest gripes through this whole message board.
Delta is forcing a minimum spend requirement beginning in 2014. The sell to you is this will help provide the best customers with more of the best perks - ie upgrades - by weeding out the ranks of Diamond and Platinum.
Well this sounds great until you look into the further advancement of the first class up-selling (more still to come). And on some fleets the reduction in first class seating - or the smaller 737-900ER replacing most 757's. Regarding the 757's staying, your odds to upgrade as a Diamond either don't change or maybe get worse - even with the sell, I would even say promise, of more benefit for fewer Medallions. Bait and switch.
And as for the 320 reconfiguration back to F16, it is nice. But there may only be 27 320's flying by the time this is done. A/C up through 3250 are slated for retirement unless Airbus comes up with a life-extension program being sought by Richard. At last check Airbus did not want to do this - and there's speculation that played a part in Airbus hacking prices even lower on the 321 order.