When you think about it, not all the elite four are really shown in the anime. Think about it like this: in Kanto all of them were shown, in Jotho none of them were shown, in Hoenn one of them was shown, Sinnoh all of them were shown and given their own episodes, and finally in Unova just Caitlin was shown. See? It's a pattern. All, none, one, all, one. So it is going according to a pattern. They probably won't be shown and I honestly feel it's too late for Shauntal, Marshal and Grimsley to appear.
So yeah, it's the All, none, one, all, one pattern. Next generation it'll be "none" for the anime.