well they're releasing them targeted to non-gw gaming stores, hobby stores and some big box stores, I would assume that kids incredibly young kids are at the whim of their parents. I got into warhammer right around 1st/2nd grade, basically ended up with the orks from a freinds box-set. at age like what 8?7?9? cant remember we were all freaked out, keeping in the mind the rarity back in the day of an up to date computer that could play decent violent shootem-ups, and the fact that it was in fact a billion times more amazing than any board game we had ever played.
In a digital age I kind of wonder if kids my age really care about physical toys/hobbies to the same extent