It costs a lot to colorize something, and in this case the size of the audience that would be interested would be too small to justify that kind of money. Kids who weren't interested in the old shows before wouldn't be interested even after the shows were colorized. Just wouldn't be worth it. Besides, I've still got bad memories of the movies Ted Turner had colorized in the '80s.
PS: there are still game shows on C-band. Check IA 5, transponder 14 H for Family Feud at 7 & 7:30 AM eastern, and IA 6, transponder 24 H for Wheel and Jeopardy at noon and 12:30 eastern, respectively. All shows feed 2 days ahead of airdate.