Take all rumors with a gain of salt.
I again here mention from my GW buddies in Memphis, that sets of sprues that are Legion specific will finally come! Chaos of course being the first sets, though i'm told Terminator and regular Space Marine sprues will be sold separately. Once the Chaos Legions sprues hit, the Legions/Chapters still dedicated to the throne of Terra shall follow.
Chaos Space Marines will receive a boxed set, with ALL the needed option upgrades included for standard gear, and new sets for Berzerkers, Noise Marines, Plague Marines and Thousand Sons will follow with MUCH nicer sculpts.
So basically, all the Legions will buy the same boxed set for the majority of their models, but to make them Legion specific, separate sprues will be sold which will include shoulder pads, heads, banners, few weapons, etc. Terminators will also get separate sprues made available to them to become Legion specific.