Not to advertise, but BA just released a zombie defence back with a zombie head. I think BF could make some awesome custom heads. Maybe they could make some that coincide with the new hair.
Erm...people have been making and selling custom heads since the dawn of minifig customization
I know Lamanda still has a business in it (she's been making Zombie heads for years), and Arealight of course does. I think the first person to sell printed customs was Cristo though. Regardless this is something that has been around for awhile that BA only just got into kinda late in the game
so no worries about "advertising". Personally I'd be all for custom heads, though given how easy it is to design decals I think that might give you greater room for personalization.