Are you talking Warhammer or Warhammer 40K. Warhammer is traditional fantasy 40K is the military sci-fi. Both by Games Workshop and using some commonalities but 2 different genres.
As for fantasy/sword & sorcery for kids, D&D is more popular than ever (thanks in part to Stranger Things) and is essentially fusion of S&S and more traditional high fantasy, and WotC/Hasbro is targeting kids with a lot of the new products such as these...
that I got my wife for Christmas (she loves D&D and children's book, so this was a no-brainer to get her). Fantasy is actually a hot genre among young reader (Harry Potter, Percy Jackson, et. al) and they've attempted to sell Conan to a kids market before with the Conan the Adventurer cartoon...
which was syndicated back in the 90s and lasted 2 seasons spawning a toy line as well. Whether it would work now, is debatable, and it certainly wouldn't be a fully Howardian interpretation. However, if they were to market Conan to a younger audience, illustrated chapter books rather than comics would be the way to go, an especially not as a monthly periodical comic. The chapter books could be young adult versions of the Howard short stories or new pastiches, but either way would do more to bring younger readers to the property than any type of new periodical comic would.
The thing to always remember regarding Conan now though is that Paradox, the owners of the Conan rights are obsessed with one goal, making more Conan movies, especially another Arnie movie and that is the only version they really care about. Knowing them, the move of the license to Marvel is more about wooing Marvel Studios to be interested in the Conan feature film than about anything else. They would license off anything else for pennies on the dollar if it meant they could get their movie made, and it's been that kind of thinking that has defined their stewardship of the Howard properties since htey acquired them.
-M