We've seen this template done successfully with the tri-color cards in the Khans of Tarkir block, such as Soulfire Grand Master
Loyal to a fault, it heeds its masters every command
As a 2/2 Defender the front does not do much
Extort comes with Sorin of House Markov and Sorin, Ravenous Neonate, and it is just a fantastic way to make enemies in Commander
Like control decks, midrange decks will gain incremental advantages over the course of the game, but where they differ is that midrange apply pressure to the opponent at all stages of the game, not just towards the end
I would expect to see Grief out of decks such as Jund, Deaths Shadow variants, Orzhov Taxes, and possibly even black-based combo or Reanimator decks