For those that don't want to be princesses there are still all sorts of options that 3D printing has. Already many blueprints for toys have been uploaded on line with options for customization, from Minecraft characters to robots.
I think that starting kids off young with 3D printing will be the best way for the industry to succeed. The sooner that a generation grows up not knowing life before 3D printing the sooner we can start taking full advantage of all the potential that it has in store.