In the first Game Show Marathon, the celebrities did play for charity, and there was a text message and Internet game for viewers, who would win the prizes that had been won by the winning celebrity in each night's game. One of the biggest problems was that most of the celebrities who played were of the grade C (or worse) level. The biggest name celebrity to play was Leslie Nielsen, who really hasn't done much in recent years, and the Match Game panel did bring back Betty White, who was a semi-regular. I'd be for getting regular contestants.
Something I noticed in another thread was that the rights to all the shows that were used were owned by Fremantle, who owns all the old Goodson-Todman shows and a few others. The ones owned by Fremantle that are currently still on the air, The Price is Right and Family Feud, were both used last time. The other game shows that are currently still on the air, Wheel, Jeopardy, and Millionaire, are all owned by Sony or Disney, so there may be a problem there. I'd guess that what will be used for the next series will be more G-T shows or other shows that Fremantle owns or can get rights to at least for the series.