Atlas cancelled the first three -8's orders in 2012 as they were all overweight. They then took delivery of 9 -8's which are now all flown by Atlas pilots and are painted in Panalpina, Ethiad, Polar, DHL, and Atlas colors.
Atlas also has an additional 13 -8 options. Bill Flynn said he intends for those (didn't say how many) to be replace some 400's.
I'm not so sure they'll be replacements anytime soon as Atlas has pulled their last two BCF's out of the desert for additional charter work this spring.

8