I think in 1974, Cindy was probably hopeful for a variety show since it would keep them off the road and as a Mother to a toddler it probably would have been easier to stay put. Cindy also had aspirations to be an actress but her personality on TV wasn't big or bold, it was sweet and pleasant. Mary had an outgoing personality and she laughed alot but I am sure on their own show it would have been reigned in. Plus, someone remarked that Mary broke character on Ed Sullivan when Diana said "go Mary". Mary was really dancing the choreography to that song. I think Diana shocked her with impromptu remark. If you notice Mary slows down a bit too. I am sure she thought Oh No! Diane is going to get me in trouble with Berry. Of course, Both Diana and Mary were relishing this upbeat song and only Flo seemed to not be going full steam.
Regardless, a variety show or even special would never have been in the cards. There was too many personnel changes and Motown wasn't really excited about them since about 1971.