Heck, I wouldn't even mind if they restricted it to Primarks that are currently running around the 40k universe, even if they are all bad (I'm not counting the "missing" primarchs such as Vulcan).
GW needs to make these models ASAP. I mean, who wouldn't want a nice deamon-possessed Fulgrim model? Or an Angron model to match the White Dwarf article's stats? It's a license to print money, I tell you.