Every other wargaming company in the world is making money selling miniatures for (basically) the Old Warhammer World -- GW want a piece of the action. Honestly, I don't know how they managed to screw up selling Bretonnians in the first place.
Like Leavhon, I feel a certain hope about the announcement. It'd be nice for the biggest wargaming company in the world to return to supporting things I like. But it's also going to be three years wait, & GW have every chance to make a mess of every part of this over the next thirty-six months. Take the new Sisters of Battle for an example: after years of being asked for new SoBs, GW promises to make them, spends two years talking about design work, finally reveal plastic Sisters that look exactly like the metal originals from the '90s, announce the release of a single box-set... & then run out within ten minutes. Perhaps there's something very clever going on, but it looks a lot like GW are capable of fumbling anything, no matter how simple.