I think, long term story telling wise, Charity/Moses was an obstacle that Debbie and Ross had to overcome. I have no doubt in my mind that when Ross was brought in by KO that Ross and Debbie were meant to be together.
It wouldn't surprise me if Debbie does get pregnant and should KO have remained as producer, they would be together when Charley comes back. We'll have to see where the next producer takes them.