This COULD work if they put the emphasis on one thing the Hanna-Barbera Flintstones did well...poke fun at contemporary pop culture. The whoe show was a bit of a send-up of the Honeymooners, Donna Reed, The Danny Thomas Show and other classic family sitcoms of the time (they eventually got around, IIRC, to having a little fun with Bewitched), and while they were at it, Bill Hanna & Joe Barbera also satirized everything from worker-boss relationships to pop music trends to TV to the consumer culture of the day. There was enough for an adult to chew on even while the kids (like I was when I was watching the show in its first run on ABC) could enjoy the characters on a silly kid level.
If Seth MacFarlane approaches it like Hanna and Barbera did, only with contemporary pop culture and social targets to poke fun at, he'll be OK and the show will work.