Mono-Black Devotion, where will it go when Return to Ravnica Block rotates out?

Hey everyone, 

       I have seen a lot of people playing Mono-Black at FNM's, and it has gotten me thinking, "What will happen after Return to Ravnica Rotates out?"

After RtR rotates, the cards gone will be as follows:

-Desecration Demon

-Pack rat

-Devour Flesh

-Underworld Connections

-Nightveil Spectre

These are often played as 4-ofs, so that is a whole 20 cards gone! And in a few more months when M15 comes out, there goes the Mutavaults and Doom-Blades

I think that the Mono-Black deck will be Much harder to build around, with Gary to amount to almost nothing with the big Black pips in the mana costs gone. I hope that when the Mono-Black decks tank, so will the Mono-Blue, and maybe Red-Green Monsters will finally rise to the top! At least I hope, who doesn't love red green monsters?

-Matthew