It's true, D&D is doing well: but Magic is more of a license to print money than ever.
I think increasingly they both are, MtG is still bigger profit wise (they call it the Magic the Crackening for a reason), but the lines between the two IPs are blurring, the popular of D&D IPs are as popular or more then their MtG counterparts, it's the collectable, competitive nature of MtG that makes it more popular, because AFR was the best selling MtG Summer set and that was with huge complaints that it was under powered.
That reminds it's been brought to my attention by someone that the Warhammer Commander Decks might be be a test to see if WotC can sell Warhammer products ahead of a possible purchase of Games Workshop itself by WotC.
It's a smart move and while very expensive purchase, it brings a ton of value to WotC and Games Workshop. WotC can do Warhammer: Sigmar/40k/classic D&D 5e setting books, more MtG Warhammer decks, secret lairs, or sets, a Birthright, Ravnica, Theros, or Forgotten Realms war game using Games Workshop skills, expand the Games Workshop's Black Library to include D&D & MtG novels lines, more D&D minis, MtG staff can help build a better secondary market for Warhammer minis, increase collectablity, and so much more.