The show has been put on hold, with no mention of when production may resume again, to accommodate MacFarlane's insanely busy schedule. In addition to the previous trifecta of Fox shows, MacFarlane is also working on Cosmos: A Space-Time Odyssey - a successor to Carl Sagan's Cosmos - and awaiting the release of his first feature film, Ted. So, it's no surprise that he would find it difficult to accommodate time for The Flintstones in there - even though the reboot is said to be a passion project for him, given his lifelong love of the show.
In addition, sources indicate that the script hasn't gone down all too well so far, with Fox Entertainment President Kevin Reilly telling MacFarlane that he liked it, but didn't love it. Whilst the show hasn't been scrapped, it has been postponed indefinitely, until such a time that MacFarlane has room in his schedule to work and rework the show's script. Several staff members have been let go, with MacFarlane looking into finding places at American Dad for others.
The idea seemed a little bizarre from the start: an animator and director renowned for his raunchy and often offensive humour, tackling the remake of such a beloved and revered show; but MacFarlane's love for the series is blatant and it would've been interesting to see where this went. Here's hoping it's back on track soon.